OMAPDSS: Provide an interface for audio support

There exist several display technologies and standards that support audio as well. Hence, it is relevant to update the DSS device driver to provide an audio interface that may be used by an audio driver or any other driver interested in the functionality. The audio_enable function is intended to prepare the relevant IP for playback (e.g., enabling an audio FIFO, taking in/out of reset some IP, enabling companion chips, etc). It is intended to be called before audio_start. The audio_disable function performs the reverse operation and is intended to be called after audio_stop. While a given DSS device driver may support audio, it is possible that for certain configurations audio is not supported (e.g., an HDMI display using a VESA video timing). The audio_supported function is intended to query whether the current configuration of the display supports audio. The audio_config function is intended to configure all the relevant audio parameters of the display. In order to make the function independent of any specific DSS device driver, a struct omap_dss_audio is defined. Its purpose is to contain all the required parameters for audio configuration. At the moment, such structure contains pointers to IEC-60958 channel status word and CEA-861 audio infoframe structures. This should be enough to support HDMI and DisplayPort, as both are based on CEA-861 and IEC-60958. The omap_dss_audio structure may be extended in the future if required. The audio_enable/disable, audio_config and audio_supported functions could be implemented as functions that may sleep. Hence, they should not be called while holding a spinlock or a readlock. The audio_start/audio_stop function is intended to effectively start/stop audio playback after the configuration has taken place. These functions are designed to be used in an atomic context. Hence, audio_start should return quickly and be called only after all the needed resources for audio playback (audio FIFOs, DMA channels, companion chips, etc) have been enabled to begin data transfers. audio_stop is designed to only stop the audio transfers. The resources used for playback are released using audio_disable. A new enum omap_dss_audio_state is introduced to help the implementations of the interface to keep track of the audio state. The initial state is _DISABLED; then, the state transitions to _CONFIGURED, and then, when it is ready to play audio, to _ENABLED. The state _PLAYING is used when the audio is being rendered. Signed-off-by: Ricardo Neri <ricardo.neri@ti.com>

OMAPDSS: Provide an interface for audio support
There exist several display technologies and standards that support audio as well. Hence, it is relevant to update the DSS device driver to provide an audio interface that may be used by an audio driver or any other driver interested in the functionality. The audio_enable function is intended to prepare the relevant IP for playback (e.g., enabling an audio FIFO, taking in/out of reset some IP, enabling companion chips, etc). It is intended to be called before audio_start. The audio_disable function performs the reverse operation and is intended to be called after audio_stop. While a given DSS device driver may support audio, it is possible that for certain configurations audio is not supported (e.g., an HDMI display using a VESA video timing). The audio_supported function is intended to query whether the current configuration of the display supports audio. The audio_config function is intended to configure all the relevant audio parameters of the display. In order to make the function independent of any specific DSS device driver, a struct omap_dss_audio is defined. Its purpose is to contain all the required parameters for audio configuration. At the moment, such structure contains pointers to IEC-60958 channel status word and CEA-861 audio infoframe structures. This should be enough to support HDMI and DisplayPort, as both are based on CEA-861 and IEC-60958. The omap_dss_audio structure may be extended in the future if required. The audio_enable/disable, audio_config and audio_supported functions could be implemented as functions that may sleep. Hence, they should not be called while holding a spinlock or a readlock. The audio_start/audio_stop function is intended to effectively start/stop audio playback after the configuration has taken place. These functions are designed to be used in an atomic context. Hence, audio_start should return quickly and be called only after all the needed resources for audio playback (audio FIFOs, DMA channels, companion chips, etc) have been enabled to begin data transfers. audio_stop is designed to only stop the audio transfers. The resources used for playback are released using audio_disable. A new enum omap_dss_audio_state is introduced to help the implementations of the interface to keep track of the audio state. The initial state is _DISABLED; then, the state transitions to _CONFIGURED, and then, when it is ready to play audio, to _ENABLED. The state _PLAYING is used when the audio is being rendered. Signed-off-by: Ricardo Neri <ricardo.neri@ti.com>
Ricardo Neri · Tomi Valkeinen
1 parent 38137c8f0c
Showing 2 changed files with 79 additions and 0 deletions Side-by-side Diff
Documentation/arm/OMAP/DSS
include/video/omapdss.h
@@ -47,6 +47,51 @@
 modelling the hardware overlays, omapdss supports virtual overlays and overlay
 managers. These can be used when updating a display with CPU or system DMA.
  
+omapdss driver support for audio
+--------------------------------
+There exist several display technologies and standards that support audio as
+well. Hence, it is relevant to update the DSS device driver to provide an audio
+interface that may be used by an audio driver or any other driver interested in
+the functionality.
+
+The audio_enable function is intended to prepare the relevant
+IP for playback (e.g., enabling an audio FIFO, taking in/out of reset
+some IP, enabling companion chips, etc). It is intended to be called before
+audio_start. The audio_disable function performs the reverse operation and is
+intended to be called after audio_stop.
+
+While a given DSS device driver may support audio, it is possible that for
+certain configurations audio is not supported (e.g., an HDMI display using a
+VESA video timing). The audio_supported function is intended to query whether
+the current configuration of the display supports audio.
+
+The audio_config function is intended to configure all the relevant audio
+parameters of the display. In order to make the function independent of any
+specific DSS device driver, a struct omap_dss_audio is defined. Its purpose
+is to contain all the required parameters for audio configuration. At the
+moment, such structure contains pointers to IEC-60958 channel status word
+and CEA-861 audio infoframe structures. This should be enough to support
+HDMI and DisplayPort, as both are based on CEA-861 and IEC-60958.
+
+The audio_enable/disable, audio_config and audio_supported functions could be
+implemented as functions that may sleep. Hence, they should not be called
+while holding a spinlock or a readlock.
+
+The audio_start/audio_stop function is intended to effectively start/stop audio
+playback after the configuration has taken place. These functions are designed
+to be used in an atomic context. Hence, audio_start should return quickly and be
+called only after all the needed resources for audio playback (audio FIFOs,
+DMA channels, companion chips, etc) have been enabled to begin data transfers.
+audio_stop is designed to only stop the audio transfers. The resources used
+for playback are released using audio_disable.
+
+The enum omap_dss_audio_state may be used to help the implementations of
+the interface to keep track of the audio state. The initial state is _DISABLED;
+then, the state transitions to _CONFIGURED, and then, when it is ready to
+play audio, to _ENABLED. The state _PLAYING is used when the audio is being
+rendered.
+
+
 Panel and controller drivers
 ----------------------------
  
@@ -51,6 +51,8 @@
  
 struct omap_dss_device;
 struct omap_overlay_manager;
+struct snd_aes_iec958;
+struct snd_cea_861_aud_if;
  
 enum omap_display_type {
 	OMAP_DISPLAY_TYPE_NONE		= 0,
@@ -158,6 +160,13 @@
 	OMAP_DSS_DISPLAY_SUSPENDED,
 };
  
+enum omap_dss_audio_state {
+	OMAP_DSS_AUDIO_DISABLED = 0,
+	OMAP_DSS_AUDIO_ENABLED,
+	OMAP_DSS_AUDIO_CONFIGURED,
+	OMAP_DSS_AUDIO_PLAYING,
+};
+
 /* XXX perhaps this should be removed */
 enum omap_dss_overlay_managers {
 	OMAP_DSS_OVL_MGR_LCD,
@@ -583,6 +592,8 @@
  
 	enum omap_dss_display_state state;
  
+	enum omap_dss_audio_state audio_state;
+
 	/* platform specific  */
 	int (*platform_enable)(struct omap_dss_device *dssdev);
 	void (*platform_disable)(struct omap_dss_device *dssdev);
@@ -595,6 +606,11 @@
 	int hpd_gpio;
 };
  
+struct omap_dss_audio {
+	struct snd_aes_iec958 *iec;
+	struct snd_cea_861_aud_if *cea;
+};
+
 struct omap_dss_driver {
 	struct device_driver driver;
  
@@ -642,6 +658,24 @@
  
 	int (*read_edid)(struct omap_dss_device *dssdev, u8 *buf, int len);
 	bool (*detect)(struct omap_dss_device *dssdev);
+
+	/*
+	 * For display drivers that support audio. This encompasses
+	 * HDMI and DisplayPort at the moment.
+	 */
+	/*
+	 * Note: These functions might sleep. Do not call while
+	 * holding a spinlock/readlock.
+	 */
+	int (*audio_enable)(struct omap_dss_device *dssdev);
+	void (*audio_disable)(struct omap_dss_device *dssdev);
+	bool (*audio_supported)(struct omap_dss_device *dssdev);
+	int (*audio_config)(struct omap_dss_device *dssdev,
+		struct omap_dss_audio *audio);
+	/* Note: These functions may not sleep */
+	int (*audio_start)(struct omap_dss_device *dssdev);
+	void (*audio_stop)(struct omap_dss_device *dssdev);
+
 };
  
 int omap_dss_register_driver(struct omap_dss_driver *);
...	...	@@ -47,6 +47,51 @@
47	47	modelling the hardware overlays, omapdss supports virtual overlays and overlay
48	48	managers. These can be used when updating a display with CPU or system DMA.
49	49
	50	+omapdss driver support for audio
	51	+--------------------------------
	52	+There exist several display technologies and standards that support audio as
	53	+well. Hence, it is relevant to update the DSS device driver to provide an audio
	54	+interface that may be used by an audio driver or any other driver interested in
	55	+the functionality.
	56	+
	57	+The audio_enable function is intended to prepare the relevant
	58	+IP for playback (e.g., enabling an audio FIFO, taking in/out of reset
	59	+some IP, enabling companion chips, etc). It is intended to be called before
	60	+audio_start. The audio_disable function performs the reverse operation and is
	61	+intended to be called after audio_stop.
	62	+
	63	+While a given DSS device driver may support audio, it is possible that for
	64	+certain configurations audio is not supported (e.g., an HDMI display using a
	65	+VESA video timing). The audio_supported function is intended to query whether
	66	+the current configuration of the display supports audio.
	67	+
	68	+The audio_config function is intended to configure all the relevant audio
	69	+parameters of the display. In order to make the function independent of any
	70	+specific DSS device driver, a struct omap_dss_audio is defined. Its purpose
	71	+is to contain all the required parameters for audio configuration. At the
	72	+moment, such structure contains pointers to IEC-60958 channel status word
	73	+and CEA-861 audio infoframe structures. This should be enough to support
	74	+HDMI and DisplayPort, as both are based on CEA-861 and IEC-60958.
	75	+
	76	+The audio_enable/disable, audio_config and audio_supported functions could be
	77	+implemented as functions that may sleep. Hence, they should not be called
	78	+while holding a spinlock or a readlock.
	79	+
	80	+The audio_start/audio_stop function is intended to effectively start/stop audio
	81	+playback after the configuration has taken place. These functions are designed
	82	+to be used in an atomic context. Hence, audio_start should return quickly and be
	83	+called only after all the needed resources for audio playback (audio FIFOs,
	84	+DMA channels, companion chips, etc) have been enabled to begin data transfers.
	85	+audio_stop is designed to only stop the audio transfers. The resources used
	86	+for playback are released using audio_disable.
	87	+
	88	+The enum omap_dss_audio_state may be used to help the implementations of
	89	+the interface to keep track of the audio state. The initial state is _DISABLED;
	90	+then, the state transitions to _CONFIGURED, and then, when it is ready to
	91	+play audio, to _ENABLED. The state _PLAYING is used when the audio is being
	92	+rendered.
	93	+
	94	+
50	95	Panel and controller drivers
51	96	----------------------------
52	97
...	...	@@ -51,6 +51,8 @@
51	51
52	52	struct omap_dss_device;
53	53	struct omap_overlay_manager;
	54	+struct snd_aes_iec958;
	55	+struct snd_cea_861_aud_if;
54	56
55	57	enum omap_display_type {
56	58	OMAP_DISPLAY_TYPE_NONE = 0,
...	...	@@ -158,6 +160,13 @@
158	160	OMAP_DSS_DISPLAY_SUSPENDED,
159	161	};
160	162
	163	+enum omap_dss_audio_state {
	164	+ OMAP_DSS_AUDIO_DISABLED = 0,
	165	+ OMAP_DSS_AUDIO_ENABLED,
	166	+ OMAP_DSS_AUDIO_CONFIGURED,
	167	+ OMAP_DSS_AUDIO_PLAYING,
	168	+};
	169	+
161	170	/* XXX perhaps this should be removed */
162	171	enum omap_dss_overlay_managers {
163	172	OMAP_DSS_OVL_MGR_LCD,
...	...	@@ -583,6 +592,8 @@
583	592
584	593	enum omap_dss_display_state state;
585	594
	595	+ enum omap_dss_audio_state audio_state;
	596	+
586	597	/* platform specific */
587	598	int (platform_enable)(struct omap_dss_device dssdev);
588	599	void (platform_disable)(struct omap_dss_device dssdev);
...	...	@@ -595,6 +606,11 @@
595	606	int hpd_gpio;
596	607	};
597	608
	609	+struct omap_dss_audio {
	610	+ struct snd_aes_iec958 *iec;
	611	+ struct snd_cea_861_aud_if *cea;
	612	+};
	613	+
598	614	struct omap_dss_driver {
599	615	struct device_driver driver;
600	616
...	...	@@ -642,6 +658,24 @@
642	658
643	659	int (read_edid)(struct omap_dss_device dssdev, u8 *buf, int len);
644	660	bool (detect)(struct omap_dss_device dssdev);
	661	+
	662	+ /*
	663	+ * For display drivers that support audio. This encompasses
	664	+ * HDMI and DisplayPort at the moment.
	665	+ */
	666	+ /*
	667	+ * Note: These functions might sleep. Do not call while
	668	+ * holding a spinlock/readlock.
	669	+ */
	670	+ int (audio_enable)(struct omap_dss_device dssdev);
	671	+ void (audio_disable)(struct omap_dss_device dssdev);
	672	+ bool (audio_supported)(struct omap_dss_device dssdev);
	673	+ int (audio_config)(struct omap_dss_device dssdev,
	674	+ struct omap_dss_audio *audio);
	675	+ /* Note: These functions may not sleep */
	676	+ int (audio_start)(struct omap_dss_device dssdev);
	677	+ void (audio_stop)(struct omap_dss_device dssdev);
	678	+
645	679	};
646	680
647	681	int omap_dss_register_driver(struct omap_dss_driver *);