/*
   * Copyright © 2006-2010 Intel Corporation
   * Copyright (c) 2006 Dave Airlie <airlied@linux.ie>
   *
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the "Software"),
   * to deal in the Software without restriction, including without limitation
   * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   * and/or sell copies of the Software, and to permit persons to whom the
   * Software is furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice (including the next
   * paragraph) shall be included in all copies or substantial portions of the
   * Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
   * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
   * DEALINGS IN THE SOFTWARE.
   *
   * Authors:
   *	Eric Anholt <eric@anholt.net>
   *      Dave Airlie <airlied@linux.ie>
   *      Jesse Barnes <jesse.barnes@intel.com>
   *      Chris Wilson <chris@chris-wilson.co.uk>
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/moduleparam.h>

  #include "intel_drv.h"
  
  void

  intel_fixed_panel_mode(const struct drm_display_mode *fixed_mode,

  		       struct drm_display_mode *adjusted_mode)
  {

  	drm_mode_copy(adjusted_mode, fixed_mode);

  
  	drm_mode_set_crtcinfo(adjusted_mode, 0);

  }

  /**
   * intel_find_panel_downclock - find the reduced downclock for LVDS in EDID
   * @dev: drm device
   * @fixed_mode : panel native mode
   * @connector: LVDS/eDP connector
   *
   * Return downclock_avail
   * Find the reduced downclock for LVDS/eDP in EDID.
   */
  struct drm_display_mode *
  intel_find_panel_downclock(struct drm_device *dev,
  			struct drm_display_mode *fixed_mode,
  			struct drm_connector *connector)
  {
  	struct drm_display_mode *scan, *tmp_mode;
  	int temp_downclock;
  
  	temp_downclock = fixed_mode->clock;
  	tmp_mode = NULL;
  
  	list_for_each_entry(scan, &connector->probed_modes, head) {
  		/*
  		 * If one mode has the same resolution with the fixed_panel
  		 * mode while they have the different refresh rate, it means
  		 * that the reduced downclock is found. In such
  		 * case we can set the different FPx0/1 to dynamically select
  		 * between low and high frequency.
  		 */
  		if (scan->hdisplay == fixed_mode->hdisplay &&
  		    scan->hsync_start == fixed_mode->hsync_start &&
  		    scan->hsync_end == fixed_mode->hsync_end &&
  		    scan->htotal == fixed_mode->htotal &&
  		    scan->vdisplay == fixed_mode->vdisplay &&
  		    scan->vsync_start == fixed_mode->vsync_start &&
  		    scan->vsync_end == fixed_mode->vsync_end &&
  		    scan->vtotal == fixed_mode->vtotal) {
  			if (scan->clock < temp_downclock) {
  				/*
  				 * The downclock is already found. But we
  				 * expect to find the lower downclock.
  				 */
  				temp_downclock = scan->clock;
  				tmp_mode = scan;
  			}
  		}
  	}
  
  	if (temp_downclock < fixed_mode->clock)
  		return drm_mode_duplicate(dev, tmp_mode);
  	else
  		return NULL;
  }

  /* adjusted_mode has been preset to be the panel's fixed mode */
  void

  intel_pch_panel_fitting(struct intel_crtc *intel_crtc,
  			struct intel_crtc_config *pipe_config,
  			int fitting_mode)

  {

  	struct drm_display_mode *adjusted_mode;

  	int x, y, width, height;

  	adjusted_mode = &pipe_config->adjusted_mode;

  	x = y = width = height = 0;
  
  	/* Native modes don't need fitting */

  	if (adjusted_mode->hdisplay == pipe_config->pipe_src_w &&
  	    adjusted_mode->vdisplay == pipe_config->pipe_src_h)

  		goto done;
  
  	switch (fitting_mode) {
  	case DRM_MODE_SCALE_CENTER:

  		width = pipe_config->pipe_src_w;
  		height = pipe_config->pipe_src_h;

  		x = (adjusted_mode->hdisplay - width + 1)/2;
  		y = (adjusted_mode->vdisplay - height + 1)/2;
  		break;
  
  	case DRM_MODE_SCALE_ASPECT:
  		/* Scale but preserve the aspect ratio */
  		{

  			u32 scaled_width = adjusted_mode->hdisplay
  				* pipe_config->pipe_src_h;
  			u32 scaled_height = pipe_config->pipe_src_w
  				* adjusted_mode->vdisplay;

  			if (scaled_width > scaled_height) { /* pillar */

  				width = scaled_height / pipe_config->pipe_src_h;

  				if (width & 1)

  					width++;

  				x = (adjusted_mode->hdisplay - width + 1) / 2;
  				y = 0;
  				height = adjusted_mode->vdisplay;
  			} else if (scaled_width < scaled_height) { /* letter */

  				height = scaled_width / pipe_config->pipe_src_w;

  				if (height & 1)
  				    height++;

  				y = (adjusted_mode->vdisplay - height + 1) / 2;
  				x = 0;
  				width = adjusted_mode->hdisplay;
  			} else {
  				x = y = 0;
  				width = adjusted_mode->hdisplay;
  				height = adjusted_mode->vdisplay;
  			}
  		}
  		break;

  	case DRM_MODE_SCALE_FULLSCREEN:
  		x = y = 0;
  		width = adjusted_mode->hdisplay;
  		height = adjusted_mode->vdisplay;
  		break;

  
  	default:
  		WARN(1, "bad panel fit mode: %d
  ", fitting_mode);
  		return;

  	}
  
  done:

  	pipe_config->pch_pfit.pos = (x << 16) | y;
  	pipe_config->pch_pfit.size = (width << 16) | height;

  	pipe_config->pch_pfit.enabled = pipe_config->pch_pfit.size != 0;

  }

  static void
  centre_horizontally(struct drm_display_mode *mode,
  		    int width)
  {
  	u32 border, sync_pos, blank_width, sync_width;
  
  	/* keep the hsync and hblank widths constant */
  	sync_width = mode->crtc_hsync_end - mode->crtc_hsync_start;
  	blank_width = mode->crtc_hblank_end - mode->crtc_hblank_start;
  	sync_pos = (blank_width - sync_width + 1) / 2;
  
  	border = (mode->hdisplay - width + 1) / 2;
  	border += border & 1; /* make the border even */
  
  	mode->crtc_hdisplay = width;
  	mode->crtc_hblank_start = width + border;
  	mode->crtc_hblank_end = mode->crtc_hblank_start + blank_width;
  
  	mode->crtc_hsync_start = mode->crtc_hblank_start + sync_pos;
  	mode->crtc_hsync_end = mode->crtc_hsync_start + sync_width;
  }
  
  static void
  centre_vertically(struct drm_display_mode *mode,
  		  int height)
  {
  	u32 border, sync_pos, blank_width, sync_width;
  
  	/* keep the vsync and vblank widths constant */
  	sync_width = mode->crtc_vsync_end - mode->crtc_vsync_start;
  	blank_width = mode->crtc_vblank_end - mode->crtc_vblank_start;
  	sync_pos = (blank_width - sync_width + 1) / 2;
  
  	border = (mode->vdisplay - height + 1) / 2;
  
  	mode->crtc_vdisplay = height;
  	mode->crtc_vblank_start = height + border;
  	mode->crtc_vblank_end = mode->crtc_vblank_start + blank_width;
  
  	mode->crtc_vsync_start = mode->crtc_vblank_start + sync_pos;
  	mode->crtc_vsync_end = mode->crtc_vsync_start + sync_width;
  }
  
  static inline u32 panel_fitter_scaling(u32 source, u32 target)
  {
  	/*
  	 * Floating point operation is not supported. So the FACTOR
  	 * is defined, which can avoid the floating point computation
  	 * when calculating the panel ratio.
  	 */
  #define ACCURACY 12
  #define FACTOR (1 << ACCURACY)
  	u32 ratio = source * FACTOR / target;
  	return (FACTOR * ratio + FACTOR/2) / FACTOR;
  }

  static void i965_scale_aspect(struct intel_crtc_config *pipe_config,
  			      u32 *pfit_control)
  {
  	struct drm_display_mode *adjusted_mode = &pipe_config->adjusted_mode;
  	u32 scaled_width = adjusted_mode->hdisplay *
  		pipe_config->pipe_src_h;
  	u32 scaled_height = pipe_config->pipe_src_w *
  		adjusted_mode->vdisplay;
  
  	/* 965+ is easy, it does everything in hw */
  	if (scaled_width > scaled_height)
  		*pfit_control |= PFIT_ENABLE |
  			PFIT_SCALING_PILLAR;
  	else if (scaled_width < scaled_height)
  		*pfit_control |= PFIT_ENABLE |
  			PFIT_SCALING_LETTER;
  	else if (adjusted_mode->hdisplay != pipe_config->pipe_src_w)
  		*pfit_control |= PFIT_ENABLE | PFIT_SCALING_AUTO;
  }
  
  static void i9xx_scale_aspect(struct intel_crtc_config *pipe_config,
  			      u32 *pfit_control, u32 *pfit_pgm_ratios,
  			      u32 *border)
  {
  	struct drm_display_mode *adjusted_mode = &pipe_config->adjusted_mode;
  	u32 scaled_width = adjusted_mode->hdisplay *
  		pipe_config->pipe_src_h;
  	u32 scaled_height = pipe_config->pipe_src_w *
  		adjusted_mode->vdisplay;
  	u32 bits;
  
  	/*
  	 * For earlier chips we have to calculate the scaling
  	 * ratio by hand and program it into the
  	 * PFIT_PGM_RATIO register
  	 */
  	if (scaled_width > scaled_height) { /* pillar */
  		centre_horizontally(adjusted_mode,
  				    scaled_height /
  				    pipe_config->pipe_src_h);
  
  		*border = LVDS_BORDER_ENABLE;
  		if (pipe_config->pipe_src_h != adjusted_mode->vdisplay) {
  			bits = panel_fitter_scaling(pipe_config->pipe_src_h,
  						    adjusted_mode->vdisplay);
  
  			*pfit_pgm_ratios |= (bits << PFIT_HORIZ_SCALE_SHIFT |
  					     bits << PFIT_VERT_SCALE_SHIFT);
  			*pfit_control |= (PFIT_ENABLE |
  					  VERT_INTERP_BILINEAR |
  					  HORIZ_INTERP_BILINEAR);
  		}
  	} else if (scaled_width < scaled_height) { /* letter */
  		centre_vertically(adjusted_mode,
  				  scaled_width /
  				  pipe_config->pipe_src_w);
  
  		*border = LVDS_BORDER_ENABLE;
  		if (pipe_config->pipe_src_w != adjusted_mode->hdisplay) {
  			bits = panel_fitter_scaling(pipe_config->pipe_src_w,
  						    adjusted_mode->hdisplay);
  
  			*pfit_pgm_ratios |= (bits << PFIT_HORIZ_SCALE_SHIFT |
  					     bits << PFIT_VERT_SCALE_SHIFT);
  			*pfit_control |= (PFIT_ENABLE |
  					  VERT_INTERP_BILINEAR |
  					  HORIZ_INTERP_BILINEAR);
  		}
  	} else {
  		/* Aspects match, Let hw scale both directions */
  		*pfit_control |= (PFIT_ENABLE |
  				  VERT_AUTO_SCALE | HORIZ_AUTO_SCALE |
  				  VERT_INTERP_BILINEAR |
  				  HORIZ_INTERP_BILINEAR);
  	}
  }

  void intel_gmch_panel_fitting(struct intel_crtc *intel_crtc,
  			      struct intel_crtc_config *pipe_config,
  			      int fitting_mode)
  {
  	struct drm_device *dev = intel_crtc->base.dev;

  	u32 pfit_control = 0, pfit_pgm_ratios = 0, border = 0;

  	struct drm_display_mode *adjusted_mode;

  	adjusted_mode = &pipe_config->adjusted_mode;
  
  	/* Native modes don't need fitting */

  	if (adjusted_mode->hdisplay == pipe_config->pipe_src_w &&
  	    adjusted_mode->vdisplay == pipe_config->pipe_src_h)

  		goto out;
  
  	switch (fitting_mode) {
  	case DRM_MODE_SCALE_CENTER:
  		/*
  		 * For centered modes, we have to calculate border widths &
  		 * heights and modify the values programmed into the CRTC.
  		 */

  		centre_horizontally(adjusted_mode, pipe_config->pipe_src_w);
  		centre_vertically(adjusted_mode, pipe_config->pipe_src_h);

  		border = LVDS_BORDER_ENABLE;
  		break;
  	case DRM_MODE_SCALE_ASPECT:
  		/* Scale but preserve the aspect ratio */

  		if (INTEL_INFO(dev)->gen >= 4)
  			i965_scale_aspect(pipe_config, &pfit_control);
  		else
  			i9xx_scale_aspect(pipe_config, &pfit_control,
  					  &pfit_pgm_ratios, &border);

  		break;

  	case DRM_MODE_SCALE_FULLSCREEN:
  		/*
  		 * Full scaling, even if it changes the aspect ratio.
  		 * Fortunately this is all done for us in hw.
  		 */

  		if (pipe_config->pipe_src_h != adjusted_mode->vdisplay ||
  		    pipe_config->pipe_src_w != adjusted_mode->hdisplay) {

  			pfit_control |= PFIT_ENABLE;
  			if (INTEL_INFO(dev)->gen >= 4)
  				pfit_control |= PFIT_SCALING_AUTO;
  			else
  				pfit_control |= (VERT_AUTO_SCALE |
  						 VERT_INTERP_BILINEAR |
  						 HORIZ_AUTO_SCALE |
  						 HORIZ_INTERP_BILINEAR);
  		}
  		break;

  	default:
  		WARN(1, "bad panel fit mode: %d
  ", fitting_mode);
  		return;

  	}
  
  	/* 965+ wants fuzzy fitting */
  	/* FIXME: handle multiple panels by failing gracefully */
  	if (INTEL_INFO(dev)->gen >= 4)
  		pfit_control |= ((intel_crtc->pipe << PFIT_PIPE_SHIFT) |
  				 PFIT_FILTER_FUZZY);
  
  out:
  	if ((pfit_control & PFIT_ENABLE) == 0) {
  		pfit_control = 0;
  		pfit_pgm_ratios = 0;
  	}

  	/* Make sure pre-965 set dither correctly for 18bpp panels. */
  	if (INTEL_INFO(dev)->gen < 4 && pipe_config->pipe_bpp == 18)
  		pfit_control |= PANEL_8TO6_DITHER_ENABLE;

  	pipe_config->gmch_pfit.control = pfit_control;
  	pipe_config->gmch_pfit.pgm_ratios = pfit_pgm_ratios;

  	pipe_config->gmch_pfit.lvds_border_bits = border;

  }

  enum drm_connector_status
  intel_panel_detect(struct drm_device *dev)
  {
  	struct drm_i915_private *dev_priv = dev->dev_private;
  
  	/* Assume that the BIOS does not lie through the OpRegion... */
  	if (!i915.panel_ignore_lid && dev_priv->opregion.lid_state) {
  		return ioread32(dev_priv->opregion.lid_state) & 0x1 ?
  			connector_status_connected :
  			connector_status_disconnected;
  	}
  
  	switch (i915.panel_ignore_lid) {
  	case -2:
  		return connector_status_connected;
  	case -1:
  		return connector_status_disconnected;
  	default:
  		return connector_status_unknown;
  	}
  }

  /**
   * scale - scale values from one range to another
   *
   * @source_val: value in range [@source_min..@source_max]
   *
   * Return @source_val in range [@source_min..@source_max] scaled to range
   * [@target_min..@target_max].
   */
  static uint32_t scale(uint32_t source_val,
  		      uint32_t source_min, uint32_t source_max,
  		      uint32_t target_min, uint32_t target_max)
  {
  	uint64_t target_val;
  
  	WARN_ON(source_min > source_max);
  	WARN_ON(target_min > target_max);
  
  	/* defensive */
  	source_val = clamp(source_val, source_min, source_max);
  
  	/* avoid overflows */

  	target_val = DIV_ROUND_CLOSEST_ULL((uint64_t)(source_val - source_min) *
  			(target_max - target_min), source_max - source_min);

  	target_val += target_min;
  
  	return target_val;
  }
  
  /* Scale user_level in range [0..user_max] to [hw_min..hw_max]. */
  static inline u32 scale_user_to_hw(struct intel_connector *connector,
  				   u32 user_level, u32 user_max)
  {
  	struct intel_panel *panel = &connector->panel;
  
  	return scale(user_level, 0, user_max,
  		     panel->backlight.min, panel->backlight.max);
  }
  
  /* Scale user_level in range [0..user_max] to [0..hw_max], clamping the result
   * to [hw_min..hw_max]. */
  static inline u32 clamp_user_to_hw(struct intel_connector *connector,
  				   u32 user_level, u32 user_max)
  {
  	struct intel_panel *panel = &connector->panel;
  	u32 hw_level;
  
  	hw_level = scale(user_level, 0, user_max, 0, panel->backlight.max);
  	hw_level = clamp(hw_level, panel->backlight.min, panel->backlight.max);
  
  	return hw_level;
  }
  
  /* Scale hw_level in range [hw_min..hw_max] to [0..user_max]. */
  static inline u32 scale_hw_to_user(struct intel_connector *connector,
  				   u32 hw_level, u32 user_max)
  {
  	struct intel_panel *panel = &connector->panel;
  
  	return scale(hw_level, panel->backlight.min, panel->backlight.max,
  		     0, user_max);
  }

  static u32 intel_panel_compute_brightness(struct intel_connector *connector,
  					  u32 val)

  {

  	struct drm_device *dev = connector->base.dev;

  	struct drm_i915_private *dev_priv = dev->dev_private;

  	struct intel_panel *panel = &connector->panel;
  
  	WARN_ON(panel->backlight.max == 0);

  	if (i915.invert_brightness < 0)

  		return val;

  	if (i915.invert_brightness > 0 ||

  	    dev_priv->quirks & QUIRK_INVERT_BRIGHTNESS) {

  		return panel->backlight.max - val;

  	}

  
  	return val;
  }

  static u32 bdw_get_backlight(struct intel_connector *connector)

  {

  	struct drm_device *dev = connector->base.dev;

  	struct drm_i915_private *dev_priv = dev->dev_private;

  	return I915_READ(BLC_PWM_PCH_CTL2) & BACKLIGHT_DUTY_CYCLE_MASK;
  }

  static u32 pch_get_backlight(struct intel_connector *connector)

  {

  	struct drm_device *dev = connector->base.dev;

  	struct drm_i915_private *dev_priv = dev->dev_private;

  	return I915_READ(BLC_PWM_CPU_CTL) & BACKLIGHT_DUTY_CYCLE_MASK;
  }

  static u32 i9xx_get_backlight(struct intel_connector *connector)
  {
  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;

  	struct intel_panel *panel = &connector->panel;

  	u32 val;

  	val = I915_READ(BLC_PWM_CTL) & BACKLIGHT_DUTY_CYCLE_MASK;
  	if (INTEL_INFO(dev)->gen < 4)
  		val >>= 1;

  	if (panel->backlight.combination_mode) {

  		u8 lbpc;

  		pci_read_config_byte(dev->pdev, PCI_LBPC, &lbpc);
  		val *= lbpc;

  	}

  	return val;
  }
  
  static u32 _vlv_get_backlight(struct drm_device *dev, enum pipe pipe)
  {
  	struct drm_i915_private *dev_priv = dev->dev_private;
  
  	return I915_READ(VLV_BLC_PWM_CTL(pipe)) & BACKLIGHT_DUTY_CYCLE_MASK;
  }
  
  static u32 vlv_get_backlight(struct intel_connector *connector)
  {
  	struct drm_device *dev = connector->base.dev;
  	enum pipe pipe = intel_get_pipe_from_connector(connector);
  
  	return _vlv_get_backlight(dev, pipe);
  }
  
  static u32 intel_panel_get_backlight(struct intel_connector *connector)
  {
  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;
  	u32 val;
  	unsigned long flags;
  
  	spin_lock_irqsave(&dev_priv->backlight_lock, flags);
  
  	val = dev_priv->display.get_backlight(connector);
  	val = intel_panel_compute_brightness(connector, val);

  	spin_unlock_irqrestore(&dev_priv->backlight_lock, flags);

  	DRM_DEBUG_DRIVER("get backlight PWM = %d
  ", val);
  	return val;
  }

  static void bdw_set_backlight(struct intel_connector *connector, u32 level)

  {

  	struct drm_device *dev = connector->base.dev;

  	struct drm_i915_private *dev_priv = dev->dev_private;
  	u32 val = I915_READ(BLC_PWM_PCH_CTL2) & ~BACKLIGHT_DUTY_CYCLE_MASK;
  	I915_WRITE(BLC_PWM_PCH_CTL2, val | level);
  }

  static void pch_set_backlight(struct intel_connector *connector, u32 level)

  {

  	struct drm_device *dev = connector->base.dev;

  	struct drm_i915_private *dev_priv = dev->dev_private;

  	u32 tmp;
  
  	tmp = I915_READ(BLC_PWM_CPU_CTL) & ~BACKLIGHT_DUTY_CYCLE_MASK;
  	I915_WRITE(BLC_PWM_CPU_CTL, tmp | level);

  }

  static void i9xx_set_backlight(struct intel_connector *connector, u32 level)

  {

  	struct drm_device *dev = connector->base.dev;

  	struct drm_i915_private *dev_priv = dev->dev_private;

  	struct intel_panel *panel = &connector->panel;

  	u32 tmp, mask;

  	WARN_ON(panel->backlight.max == 0);

  	if (panel->backlight.combination_mode) {

  		u8 lbpc;

  		lbpc = level * 0xfe / panel->backlight.max + 1;

  		level /= lbpc;
  		pci_write_config_byte(dev->pdev, PCI_LBPC, lbpc);
  	}

  	if (IS_GEN4(dev)) {
  		mask = BACKLIGHT_DUTY_CYCLE_MASK;
  	} else {

  		level <<= 1;

  		mask = BACKLIGHT_DUTY_CYCLE_MASK_PNV;
  	}

  	tmp = I915_READ(BLC_PWM_CTL) & ~mask;

  	I915_WRITE(BLC_PWM_CTL, tmp | level);
  }
  
  static void vlv_set_backlight(struct intel_connector *connector, u32 level)
  {
  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;
  	enum pipe pipe = intel_get_pipe_from_connector(connector);
  	u32 tmp;
  
  	tmp = I915_READ(VLV_BLC_PWM_CTL(pipe)) & ~BACKLIGHT_DUTY_CYCLE_MASK;
  	I915_WRITE(VLV_BLC_PWM_CTL(pipe), tmp | level);
  }
  
  static void
  intel_panel_actually_set_backlight(struct intel_connector *connector, u32 level)
  {
  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;
  
  	DRM_DEBUG_DRIVER("set backlight PWM = %d
  ", level);
  
  	level = intel_panel_compute_brightness(connector, level);
  	dev_priv->display.set_backlight(connector, level);

  }

  /* set backlight brightness to level in range [0..max], scaling wrt hw min */
  static void intel_panel_set_backlight(struct intel_connector *connector,
  				      u32 user_level, u32 user_max)

  {

  	struct drm_device *dev = connector->base.dev;

  	struct drm_i915_private *dev_priv = dev->dev_private;

  	struct intel_panel *panel = &connector->panel;

  	enum pipe pipe = intel_get_pipe_from_connector(connector);

  	u32 hw_level;

  	unsigned long flags;

  	if (!panel->backlight.present || pipe == INVALID_PIPE)

  		return;

  	spin_lock_irqsave(&dev_priv->backlight_lock, flags);

  	WARN_ON(panel->backlight.max == 0);

  	hw_level = scale_user_to_hw(connector, user_level, user_max);
  	panel->backlight.level = hw_level;
  
  	if (panel->backlight.enabled)
  		intel_panel_actually_set_backlight(connector, hw_level);
  
  	spin_unlock_irqrestore(&dev_priv->backlight_lock, flags);
  }
  
  /* set backlight brightness to level in range [0..max], assuming hw min is
   * respected.
   */
  void intel_panel_set_backlight_acpi(struct intel_connector *connector,
  				    u32 user_level, u32 user_max)
  {
  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;
  	struct intel_panel *panel = &connector->panel;
  	enum pipe pipe = intel_get_pipe_from_connector(connector);
  	u32 hw_level;
  	unsigned long flags;
  
  	if (!panel->backlight.present || pipe == INVALID_PIPE)
  		return;
  
  	spin_lock_irqsave(&dev_priv->backlight_lock, flags);
  
  	WARN_ON(panel->backlight.max == 0);
  
  	hw_level = clamp_user_to_hw(connector, user_level, user_max);
  	panel->backlight.level = hw_level;

  	if (panel->backlight.device)

  		panel->backlight.device->props.brightness =
  			scale_hw_to_user(connector,
  					 panel->backlight.level,
  					 panel->backlight.device->props.max_brightness);

  	if (panel->backlight.enabled)

  		intel_panel_actually_set_backlight(connector, hw_level);

  	spin_unlock_irqrestore(&dev_priv->backlight_lock, flags);

  }

  static void pch_disable_backlight(struct intel_connector *connector)
  {
  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;
  	u32 tmp;

  	intel_panel_actually_set_backlight(connector, 0);

  	tmp = I915_READ(BLC_PWM_CPU_CTL2);
  	I915_WRITE(BLC_PWM_CPU_CTL2, tmp & ~BLM_PWM_ENABLE);
  
  	tmp = I915_READ(BLC_PWM_PCH_CTL1);
  	I915_WRITE(BLC_PWM_PCH_CTL1, tmp & ~BLM_PCH_PWM_ENABLE);
  }

  static void i9xx_disable_backlight(struct intel_connector *connector)
  {
  	intel_panel_actually_set_backlight(connector, 0);
  }

  static void i965_disable_backlight(struct intel_connector *connector)
  {
  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;
  	u32 tmp;

  	intel_panel_actually_set_backlight(connector, 0);

  	tmp = I915_READ(BLC_PWM_CTL2);
  	I915_WRITE(BLC_PWM_CTL2, tmp & ~BLM_PWM_ENABLE);
  }
  
  static void vlv_disable_backlight(struct intel_connector *connector)
  {
  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;
  	enum pipe pipe = intel_get_pipe_from_connector(connector);
  	u32 tmp;

  	intel_panel_actually_set_backlight(connector, 0);

  	tmp = I915_READ(VLV_BLC_PWM_CTL2(pipe));
  	I915_WRITE(VLV_BLC_PWM_CTL2(pipe), tmp & ~BLM_PWM_ENABLE);
  }

  void intel_panel_disable_backlight(struct intel_connector *connector)

  {

  	struct drm_device *dev = connector->base.dev;

  	struct drm_i915_private *dev_priv = dev->dev_private;

  	struct intel_panel *panel = &connector->panel;

  	enum pipe pipe = intel_get_pipe_from_connector(connector);

  	unsigned long flags;

  	if (!panel->backlight.present || pipe == INVALID_PIPE)

  		return;

  	/*
  	 * Do not disable backlight on the vgaswitcheroo path. When switching
  	 * away from i915, the other client may depend on i915 to handle the
  	 * backlight. This will leave the backlight on unnecessarily when
  	 * another client is not activated.
  	 */
  	if (dev->switch_power_state == DRM_SWITCH_POWER_CHANGING) {
  		DRM_DEBUG_DRIVER("Skipping backlight disable on vga switch
  ");
  		return;
  	}

  	spin_lock_irqsave(&dev_priv->backlight_lock, flags);

  	if (panel->backlight.device)
  		panel->backlight.device->props.power = FB_BLANK_POWERDOWN;

  	panel->backlight.enabled = false;

  	dev_priv->display.disable_backlight(connector);

  	spin_unlock_irqrestore(&dev_priv->backlight_lock, flags);
  }

  static void bdw_enable_backlight(struct intel_connector *connector)
  {
  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;
  	struct intel_panel *panel = &connector->panel;
  	u32 pch_ctl1, pch_ctl2;
  
  	pch_ctl1 = I915_READ(BLC_PWM_PCH_CTL1);
  	if (pch_ctl1 & BLM_PCH_PWM_ENABLE) {
  		DRM_DEBUG_KMS("pch backlight already enabled
  ");
  		pch_ctl1 &= ~BLM_PCH_PWM_ENABLE;
  		I915_WRITE(BLC_PWM_PCH_CTL1, pch_ctl1);
  	}

  	pch_ctl2 = panel->backlight.max << 16;
  	I915_WRITE(BLC_PWM_PCH_CTL2, pch_ctl2);

  	pch_ctl1 = 0;
  	if (panel->backlight.active_low_pwm)
  		pch_ctl1 |= BLM_PCH_POLARITY;

  	/* BDW always uses the pch pwm controls. */
  	pch_ctl1 |= BLM_PCH_OVERRIDE_ENABLE;
  
  	I915_WRITE(BLC_PWM_PCH_CTL1, pch_ctl1);
  	POSTING_READ(BLC_PWM_PCH_CTL1);
  	I915_WRITE(BLC_PWM_PCH_CTL1, pch_ctl1 | BLM_PCH_PWM_ENABLE);
  
  	/* This won't stick until the above enable. */
  	intel_panel_actually_set_backlight(connector, panel->backlight.level);

  }

  static void pch_enable_backlight(struct intel_connector *connector)
  {
  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;

  	struct intel_panel *panel = &connector->panel;

  	enum pipe pipe = intel_get_pipe_from_connector(connector);
  	enum transcoder cpu_transcoder =
  		intel_pipe_to_cpu_transcoder(dev_priv, pipe);

  	u32 cpu_ctl2, pch_ctl1, pch_ctl2;

  	cpu_ctl2 = I915_READ(BLC_PWM_CPU_CTL2);
  	if (cpu_ctl2 & BLM_PWM_ENABLE) {

  		DRM_DEBUG_KMS("cpu backlight already enabled
  ");

  		cpu_ctl2 &= ~BLM_PWM_ENABLE;
  		I915_WRITE(BLC_PWM_CPU_CTL2, cpu_ctl2);
  	}

  	pch_ctl1 = I915_READ(BLC_PWM_PCH_CTL1);
  	if (pch_ctl1 & BLM_PCH_PWM_ENABLE) {
  		DRM_DEBUG_KMS("pch backlight already enabled
  ");
  		pch_ctl1 &= ~BLM_PCH_PWM_ENABLE;
  		I915_WRITE(BLC_PWM_PCH_CTL1, pch_ctl1);
  	}

  
  	if (cpu_transcoder == TRANSCODER_EDP)

  		cpu_ctl2 = BLM_TRANSCODER_EDP;

  	else

  		cpu_ctl2 = BLM_PIPE(cpu_transcoder);
  	I915_WRITE(BLC_PWM_CPU_CTL2, cpu_ctl2);

  	POSTING_READ(BLC_PWM_CPU_CTL2);

  	I915_WRITE(BLC_PWM_CPU_CTL2, cpu_ctl2 | BLM_PWM_ENABLE);

  	/* This won't stick until the above enable. */

  	intel_panel_actually_set_backlight(connector, panel->backlight.level);

  
  	pch_ctl2 = panel->backlight.max << 16;
  	I915_WRITE(BLC_PWM_PCH_CTL2, pch_ctl2);

  	pch_ctl1 = 0;
  	if (panel->backlight.active_low_pwm)
  		pch_ctl1 |= BLM_PCH_POLARITY;

  	I915_WRITE(BLC_PWM_PCH_CTL1, pch_ctl1);
  	POSTING_READ(BLC_PWM_PCH_CTL1);
  	I915_WRITE(BLC_PWM_PCH_CTL1, pch_ctl1 | BLM_PCH_PWM_ENABLE);

  }
  
  static void i9xx_enable_backlight(struct intel_connector *connector)
  {

  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;

  	struct intel_panel *panel = &connector->panel;

  	u32 ctl, freq;
  
  	ctl = I915_READ(BLC_PWM_CTL);
  	if (ctl & BACKLIGHT_DUTY_CYCLE_MASK_PNV) {

  		DRM_DEBUG_KMS("backlight already enabled
  ");

  		I915_WRITE(BLC_PWM_CTL, 0);
  	}

  	freq = panel->backlight.max;
  	if (panel->backlight.combination_mode)
  		freq /= 0xff;
  
  	ctl = freq << 17;

  	if (panel->backlight.combination_mode)

  		ctl |= BLM_LEGACY_MODE;
  	if (IS_PINEVIEW(dev) && panel->backlight.active_low_pwm)
  		ctl |= BLM_POLARITY_PNV;
  
  	I915_WRITE(BLC_PWM_CTL, ctl);
  	POSTING_READ(BLC_PWM_CTL);
  
  	/* XXX: combine this into above write? */

  	intel_panel_actually_set_backlight(connector, panel->backlight.level);

  }

  static void i965_enable_backlight(struct intel_connector *connector)
  {
  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;

  	struct intel_panel *panel = &connector->panel;

  	enum pipe pipe = intel_get_pipe_from_connector(connector);

  	u32 ctl, ctl2, freq;

  	ctl2 = I915_READ(BLC_PWM_CTL2);
  	if (ctl2 & BLM_PWM_ENABLE) {

  		DRM_DEBUG_KMS("backlight already enabled
  ");

  		ctl2 &= ~BLM_PWM_ENABLE;
  		I915_WRITE(BLC_PWM_CTL2, ctl2);
  	}

  	freq = panel->backlight.max;
  	if (panel->backlight.combination_mode)
  		freq /= 0xff;

  	ctl = freq << 16;
  	I915_WRITE(BLC_PWM_CTL, ctl);

  	ctl2 = BLM_PIPE(pipe);
  	if (panel->backlight.combination_mode)
  		ctl2 |= BLM_COMBINATION_MODE;
  	if (panel->backlight.active_low_pwm)
  		ctl2 |= BLM_POLARITY_I965;
  	I915_WRITE(BLC_PWM_CTL2, ctl2);
  	POSTING_READ(BLC_PWM_CTL2);
  	I915_WRITE(BLC_PWM_CTL2, ctl2 | BLM_PWM_ENABLE);

  
  	intel_panel_actually_set_backlight(connector, panel->backlight.level);

  }
  
  static void vlv_enable_backlight(struct intel_connector *connector)
  {
  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;

  	struct intel_panel *panel = &connector->panel;

  	enum pipe pipe = intel_get_pipe_from_connector(connector);

  	u32 ctl, ctl2;

  	ctl2 = I915_READ(VLV_BLC_PWM_CTL2(pipe));
  	if (ctl2 & BLM_PWM_ENABLE) {

  		DRM_DEBUG_KMS("backlight already enabled
  ");

  		ctl2 &= ~BLM_PWM_ENABLE;
  		I915_WRITE(VLV_BLC_PWM_CTL2(pipe), ctl2);
  	}

  	ctl = panel->backlight.max << 16;
  	I915_WRITE(VLV_BLC_PWM_CTL(pipe), ctl);

  	/* XXX: combine this into above write? */
  	intel_panel_actually_set_backlight(connector, panel->backlight.level);

  	ctl2 = 0;
  	if (panel->backlight.active_low_pwm)
  		ctl2 |= BLM_POLARITY_I965;
  	I915_WRITE(VLV_BLC_PWM_CTL2(pipe), ctl2);

  	POSTING_READ(VLV_BLC_PWM_CTL2(pipe));

  	I915_WRITE(VLV_BLC_PWM_CTL2(pipe), ctl2 | BLM_PWM_ENABLE);

  }

  void intel_panel_enable_backlight(struct intel_connector *connector)

  {

  	struct drm_device *dev = connector->base.dev;

  	struct drm_i915_private *dev_priv = dev->dev_private;

  	struct intel_panel *panel = &connector->panel;

  	enum pipe pipe = intel_get_pipe_from_connector(connector);

  	unsigned long flags;

  	if (!panel->backlight.present || pipe == INVALID_PIPE)

  		return;

  	DRM_DEBUG_KMS("pipe %c
  ", pipe_name(pipe));

  	spin_lock_irqsave(&dev_priv->backlight_lock, flags);

  	WARN_ON(panel->backlight.max == 0);

  	if (panel->backlight.level <= panel->backlight.min) {

  		panel->backlight.level = panel->backlight.max;

  		if (panel->backlight.device)
  			panel->backlight.device->props.brightness =

  				scale_hw_to_user(connector,
  						 panel->backlight.level,
  						 panel->backlight.device->props.max_brightness);

  	}

  	dev_priv->display.enable_backlight(connector);

  	panel->backlight.enabled = true;

  	if (panel->backlight.device)
  		panel->backlight.device->props.power = FB_BLANK_UNBLANK;

  	spin_unlock_irqrestore(&dev_priv->backlight_lock, flags);

  }

  #if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)

  static int intel_backlight_device_update_status(struct backlight_device *bd)

  {

  	struct intel_connector *connector = bl_get_data(bd);

  	struct intel_panel *panel = &connector->panel;

  	struct drm_device *dev = connector->base.dev;

  	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);

  	DRM_DEBUG_KMS("updating intel_backlight, brightness=%d/%d
  ",
  		      bd->props.brightness, bd->props.max_brightness);

  	intel_panel_set_backlight(connector, bd->props.brightness,

  				  bd->props.max_brightness);

  
  	/*
  	 * Allow flipping bl_power as a sub-state of enabled. Sadly the
  	 * backlight class device does not make it easy to to differentiate
  	 * between callbacks for brightness and bl_power, so our backlight_power
  	 * callback needs to take this into account.
  	 */
  	if (panel->backlight.enabled) {
  		if (panel->backlight_power) {

  			bool enable = bd->props.power == FB_BLANK_UNBLANK &&
  				bd->props.brightness != 0;

  			panel->backlight_power(connector, enable);
  		}
  	} else {
  		bd->props.power = FB_BLANK_POWERDOWN;
  	}

  	drm_modeset_unlock(&dev->mode_config.connection_mutex);

  	return 0;
  }

  static int intel_backlight_device_get_brightness(struct backlight_device *bd)

  {

  	struct intel_connector *connector = bl_get_data(bd);
  	struct drm_device *dev = connector->base.dev;

  	struct drm_i915_private *dev_priv = dev->dev_private;

  	u32 hw_level;

  	int ret;

  	intel_runtime_pm_get(dev_priv);

  	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);

  
  	hw_level = intel_panel_get_backlight(connector);
  	ret = scale_hw_to_user(connector, hw_level, bd->props.max_brightness);

  	drm_modeset_unlock(&dev->mode_config.connection_mutex);

  	intel_runtime_pm_put(dev_priv);

  	return ret;

  }

  static const struct backlight_ops intel_backlight_device_ops = {
  	.update_status = intel_backlight_device_update_status,
  	.get_brightness = intel_backlight_device_get_brightness,

  };

  static int intel_backlight_device_register(struct intel_connector *connector)

  {

  	struct intel_panel *panel = &connector->panel;

  	struct backlight_properties props;

  	if (WARN_ON(panel->backlight.device))

  		return -ENODEV;

  	WARN_ON(panel->backlight.max == 0);

  	memset(&props, 0, sizeof(props));

  	props.type = BACKLIGHT_RAW;

  
  	/*
  	 * Note: Everything should work even if the backlight device max
  	 * presented to the userspace is arbitrarily chosen.
  	 */

  	props.max_brightness = panel->backlight.max;

  	props.brightness = scale_hw_to_user(connector,
  					    panel->backlight.level,
  					    props.max_brightness);

  	if (panel->backlight.enabled)
  		props.power = FB_BLANK_UNBLANK;
  	else
  		props.power = FB_BLANK_POWERDOWN;

  	/*
  	 * Note: using the same name independent of the connector prevents
  	 * registration of multiple backlight devices in the driver.
  	 */
  	panel->backlight.device =

  		backlight_device_register("intel_backlight",

  					  connector->base.kdev,
  					  connector,
  					  &intel_backlight_device_ops, &props);

  	if (IS_ERR(panel->backlight.device)) {

  		DRM_ERROR("Failed to register backlight: %ld
  ",

  			  PTR_ERR(panel->backlight.device));
  		panel->backlight.device = NULL;

  		return -ENODEV;
  	}

  	return 0;
  }

  static void intel_backlight_device_unregister(struct intel_connector *connector)

  {

  	struct intel_panel *panel = &connector->panel;
  
  	if (panel->backlight.device) {
  		backlight_device_unregister(panel->backlight.device);
  		panel->backlight.device = NULL;

  	}

  }

  #else /* CONFIG_BACKLIGHT_CLASS_DEVICE */
  static int intel_backlight_device_register(struct intel_connector *connector)
  {
  	return 0;
  }
  static void intel_backlight_device_unregister(struct intel_connector *connector)
  {
  }
  #endif /* CONFIG_BACKLIGHT_CLASS_DEVICE */

  /*
   * Note: The setup hooks can't assume pipe is set!
   *
   * XXX: Query mode clock or hardware clock and program PWM modulation frequency
   * appropriately when it's 0. Use VBT and/or sane defaults.
   */

  static u32 get_backlight_min_vbt(struct intel_connector *connector)
  {
  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;
  	struct intel_panel *panel = &connector->panel;

  	int min;

  
  	WARN_ON(panel->backlight.max == 0);

  	/*
  	 * XXX: If the vbt value is 255, it makes min equal to max, which leads
  	 * to problems. There are such machines out there. Either our
  	 * interpretation is wrong or the vbt has bogus data. Or both. Safeguard
  	 * against this by letting the minimum be at most (arbitrarily chosen)
  	 * 25% of the max.
  	 */
  	min = clamp_t(int, dev_priv->vbt.backlight.min_brightness, 0, 64);
  	if (min != dev_priv->vbt.backlight.min_brightness) {
  		DRM_DEBUG_KMS("clamping VBT min backlight %d/255 to %d/255
  ",
  			      dev_priv->vbt.backlight.min_brightness, min);
  	}

  	/* vbt value is a coefficient in range [0..255] */

  	return scale(min, 0, 255, 0, panel->backlight.max);

  }

  static int bdw_setup_backlight(struct intel_connector *connector)

  {

  	struct drm_device *dev = connector->base.dev;

  	struct drm_i915_private *dev_priv = dev->dev_private;

  	struct intel_panel *panel = &connector->panel;
  	u32 pch_ctl1, pch_ctl2, val;
  
  	pch_ctl1 = I915_READ(BLC_PWM_PCH_CTL1);
  	panel->backlight.active_low_pwm = pch_ctl1 & BLM_PCH_POLARITY;
  
  	pch_ctl2 = I915_READ(BLC_PWM_PCH_CTL2);
  	panel->backlight.max = pch_ctl2 >> 16;
  	if (!panel->backlight.max)
  		return -ENODEV;

  	panel->backlight.min = get_backlight_min_vbt(connector);

  	val = bdw_get_backlight(connector);
  	panel->backlight.level = intel_panel_compute_brightness(connector, val);
  
  	panel->backlight.enabled = (pch_ctl1 & BLM_PCH_PWM_ENABLE) &&
  		panel->backlight.level != 0;
  
  	return 0;
  }

  static int pch_setup_backlight(struct intel_connector *connector)
  {

  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;

  	struct intel_panel *panel = &connector->panel;

  	u32 cpu_ctl2, pch_ctl1, pch_ctl2, val;

  	pch_ctl1 = I915_READ(BLC_PWM_PCH_CTL1);
  	panel->backlight.active_low_pwm = pch_ctl1 & BLM_PCH_POLARITY;
  
  	pch_ctl2 = I915_READ(BLC_PWM_PCH_CTL2);
  	panel->backlight.max = pch_ctl2 >> 16;

  	if (!panel->backlight.max)
  		return -ENODEV;

  	panel->backlight.min = get_backlight_min_vbt(connector);

  	val = pch_get_backlight(connector);
  	panel->backlight.level = intel_panel_compute_brightness(connector, val);

  	cpu_ctl2 = I915_READ(BLC_PWM_CPU_CTL2);
  	panel->backlight.enabled = (cpu_ctl2 & BLM_PWM_ENABLE) &&
  		(pch_ctl1 & BLM_PCH_PWM_ENABLE) && panel->backlight.level != 0;

  	return 0;
  }
  
  static int i9xx_setup_backlight(struct intel_connector *connector)
  {

  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;

  	struct intel_panel *panel = &connector->panel;

  	u32 ctl, val;
  
  	ctl = I915_READ(BLC_PWM_CTL);

  	if (IS_GEN2(dev) || IS_I915GM(dev) || IS_I945GM(dev))

  		panel->backlight.combination_mode = ctl & BLM_LEGACY_MODE;
  
  	if (IS_PINEVIEW(dev))
  		panel->backlight.active_low_pwm = ctl & BLM_POLARITY_PNV;
  
  	panel->backlight.max = ctl >> 17;
  	if (panel->backlight.combination_mode)
  		panel->backlight.max *= 0xff;

  	if (!panel->backlight.max)
  		return -ENODEV;

  	panel->backlight.min = get_backlight_min_vbt(connector);

  	val = i9xx_get_backlight(connector);
  	panel->backlight.level = intel_panel_compute_brightness(connector, val);

  	panel->backlight.enabled = panel->backlight.level != 0;

  	return 0;
  }
  
  static int i965_setup_backlight(struct intel_connector *connector)
  {

  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;

  	struct intel_panel *panel = &connector->panel;

  	u32 ctl, ctl2, val;
  
  	ctl2 = I915_READ(BLC_PWM_CTL2);
  	panel->backlight.combination_mode = ctl2 & BLM_COMBINATION_MODE;
  	panel->backlight.active_low_pwm = ctl2 & BLM_POLARITY_I965;
  
  	ctl = I915_READ(BLC_PWM_CTL);
  	panel->backlight.max = ctl >> 16;
  	if (panel->backlight.combination_mode)
  		panel->backlight.max *= 0xff;

  	if (!panel->backlight.max)
  		return -ENODEV;

  	panel->backlight.min = get_backlight_min_vbt(connector);

  	val = i9xx_get_backlight(connector);
  	panel->backlight.level = intel_panel_compute_brightness(connector, val);

  	panel->backlight.enabled = (ctl2 & BLM_PWM_ENABLE) &&
  		panel->backlight.level != 0;

  	return 0;
  }
  
  static int vlv_setup_backlight(struct intel_connector *connector)
  {
  	struct drm_device *dev = connector->base.dev;
  	struct drm_i915_private *dev_priv = dev->dev_private;
  	struct intel_panel *panel = &connector->panel;
  	enum pipe pipe;

  	u32 ctl, ctl2, val;

  	for_each_pipe(dev_priv, pipe) {

  		u32 cur_val = I915_READ(VLV_BLC_PWM_CTL(pipe));
  
  		/* Skip if the modulation freq is already set */
  		if (cur_val & ~BACKLIGHT_DUTY_CYCLE_MASK)
  			continue;
  
  		cur_val &= BACKLIGHT_DUTY_CYCLE_MASK;
  		I915_WRITE(VLV_BLC_PWM_CTL(pipe), (0xf42 << 16) |
  			   cur_val);
  	}

  	ctl2 = I915_READ(VLV_BLC_PWM_CTL2(PIPE_A));
  	panel->backlight.active_low_pwm = ctl2 & BLM_POLARITY_I965;
  
  	ctl = I915_READ(VLV_BLC_PWM_CTL(PIPE_A));
  	panel->backlight.max = ctl >> 16;

  	if (!panel->backlight.max)
  		return -ENODEV;

  	panel->backlight.min = get_backlight_min_vbt(connector);

  	val = _vlv_get_backlight(dev, PIPE_A);
  	panel->backlight.level = intel_panel_compute_brightness(connector, val);

  	panel->backlight.enabled = (ctl2 & BLM_PWM_ENABLE) &&
  		panel->backlight.level != 0;

  	return 0;
  }

  int intel_panel_setup_backlight(struct drm_connector *connector)

  {

  	struct drm_device *dev = connector->dev;

  	struct drm_i915_private *dev_priv = dev->dev_private;

  	struct intel_connector *intel_connector = to_intel_connector(connector);

  	struct intel_panel *panel = &intel_connector->panel;

  	unsigned long flags;
  	int ret;

  	if (!dev_priv->vbt.backlight.present) {

  		if (dev_priv->quirks & QUIRK_BACKLIGHT_PRESENT) {
  			DRM_DEBUG_KMS("no backlight present per VBT, but present per quirk
  ");
  		} else {
  			DRM_DEBUG_KMS("no backlight present per VBT
  ");
  			return 0;
  		}

  	}

  	/* set level and max in panel struct */
  	spin_lock_irqsave(&dev_priv->backlight_lock, flags);
  	ret = dev_priv->display.setup_backlight(intel_connector);
  	spin_unlock_irqrestore(&dev_priv->backlight_lock, flags);
  
  	if (ret) {
  		DRM_DEBUG_KMS("failed to setup backlight for connector %s
  ",

  			      connector->name);

  		return ret;
  	}

  	intel_backlight_device_register(intel_connector);

  	panel->backlight.present = true;

  	DRM_DEBUG_KMS("backlight initialized, %s, brightness %u/%u, "
  		      "sysfs interface %sregistered
  ",
  		      panel->backlight.enabled ? "enabled" : "disabled",
  		      panel->backlight.level, panel->backlight.max,
  		      panel->backlight.device ? "" : "not ");

  	return 0;
  }

  void intel_panel_destroy_backlight(struct drm_connector *connector)

  {

  	struct intel_connector *intel_connector = to_intel_connector(connector);

  	struct intel_panel *panel = &intel_connector->panel;

  	panel->backlight.present = false;

  	intel_backlight_device_unregister(intel_connector);

  }

  /* Set up chip specific backlight functions */
  void intel_panel_init_backlight_funcs(struct drm_device *dev)
  {
  	struct drm_i915_private *dev_priv = dev->dev_private;

  	if (IS_BROADWELL(dev)) {
  		dev_priv->display.setup_backlight = bdw_setup_backlight;
  		dev_priv->display.enable_backlight = bdw_enable_backlight;
  		dev_priv->display.disable_backlight = pch_disable_backlight;
  		dev_priv->display.set_backlight = bdw_set_backlight;
  		dev_priv->display.get_backlight = bdw_get_backlight;
  	} else if (HAS_PCH_SPLIT(dev)) {

  		dev_priv->display.setup_backlight = pch_setup_backlight;
  		dev_priv->display.enable_backlight = pch_enable_backlight;
  		dev_priv->display.disable_backlight = pch_disable_backlight;
  		dev_priv->display.set_backlight = pch_set_backlight;
  		dev_priv->display.get_backlight = pch_get_backlight;

  	} else if (IS_VALLEYVIEW(dev)) {
  		dev_priv->display.setup_backlight = vlv_setup_backlight;
  		dev_priv->display.enable_backlight = vlv_enable_backlight;
  		dev_priv->display.disable_backlight = vlv_disable_backlight;
  		dev_priv->display.set_backlight = vlv_set_backlight;
  		dev_priv->display.get_backlight = vlv_get_backlight;

  	} else if (IS_GEN4(dev)) {
  		dev_priv->display.setup_backlight = i965_setup_backlight;
  		dev_priv->display.enable_backlight = i965_enable_backlight;
  		dev_priv->display.disable_backlight = i965_disable_backlight;
  		dev_priv->display.set_backlight = i9xx_set_backlight;
  		dev_priv->display.get_backlight = i9xx_get_backlight;

  	} else {
  		dev_priv->display.setup_backlight = i9xx_setup_backlight;

  		dev_priv->display.enable_backlight = i9xx_enable_backlight;
  		dev_priv->display.disable_backlight = i9xx_disable_backlight;

  		dev_priv->display.set_backlight = i9xx_set_backlight;
  		dev_priv->display.get_backlight = i9xx_get_backlight;

  	}
  }

  int intel_panel_init(struct intel_panel *panel,

  		     struct drm_display_mode *fixed_mode,
  		     struct drm_display_mode *downclock_mode)

  {

  	panel->fixed_mode = fixed_mode;

  	panel->downclock_mode = downclock_mode;

  	return 0;
  }
  
  void intel_panel_fini(struct intel_panel *panel)
  {

  	struct intel_connector *intel_connector =
  		container_of(panel, struct intel_connector, panel);
  
  	if (panel->fixed_mode)
  		drm_mode_destroy(intel_connector->base.dev, panel->fixed_mode);

  
  	if (panel->downclock_mode)
  		drm_mode_destroy(intel_connector->base.dev,
  				panel->downclock_mode);

  }