VIDEO: amba clcd: don't disable an already disabled clock

Fix the clock enable/disable tracking in the AMBA CLCD driver so that the driver doesn't try to disable an already disabled clock, thereby causing the clock (if shared) to become unbalanced. This resolves a problem with CLCD on LPC32xx ARM platforms. Reported-by: Kevin Wells <wellsk40@gmail.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

VIDEO: amba clcd: don't disable an already disabled clock
Fix the clock enable/disable tracking in the AMBA CLCD driver so that the driver doesn't try to disable an already disabled clock, thereby causing the clock (if shared) to become unbalanced. This resolves a problem with CLCD on LPC32xx ARM platforms. Reported-by: Kevin Wells <wellsk40@gmail.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Russell King
1 parent 41e2e8fd34
Showing 2 changed files with 9 additions and 2 deletions Side-by-side Diff
drivers/video/amba-clcd.c
include/linux/amba/clcd.h
@@ -80,7 +80,10 @@
 	/*
 	 * Disable CLCD clock source.
 	 */
-	clk_disable(fb->clk);
+	if (fb->clk_enabled) {
+		fb->clk_enabled = false;
+		clk_disable(fb->clk);
+	}
 }
  
 static void clcdfb_enable(struct clcd_fb *fb, u32 cntl)
@@ -88,7 +91,10 @@
 	/*
 	 * Enable the CLCD clock source.
 	 */
-	clk_enable(fb->clk);
+	if (!fb->clk_enabled) {
+		fb->clk_enabled = true;
+		clk_enable(fb->clk);
+	}
  
 	/*
 	 * Bring up by first enabling..
@@ -150,6 +150,7 @@
 	u16			off_cntl;
 	u32			clcd_cntl;
 	u32			cmap[16];
+	bool			clk_enabled;
 };
  
 static inline void clcdfb_decode(struct clcd_fb *fb, struct clcd_regs *regs)
...	...	@@ -80,7 +80,10 @@
80	80	/*
81	81	* Disable CLCD clock source.
82	82	*/
83		- clk_disable(fb->clk);
	83	+ if (fb->clk_enabled) {
	84	+ fb->clk_enabled = false;
	85	+ clk_disable(fb->clk);
	86	+ }
84	87	}
85	88
86	89	static void clcdfb_enable(struct clcd_fb *fb, u32 cntl)
...	...	@@ -88,7 +91,10 @@
88	91	/*
89	92	* Enable the CLCD clock source.
90	93	*/
91		- clk_enable(fb->clk);
	94	+ if (!fb->clk_enabled) {
	95	+ fb->clk_enabled = true;
	96	+ clk_enable(fb->clk);
	97	+ }
92	98
93	99	/*
94	100	* Bring up by first enabling..
...	...	@@ -150,6 +150,7 @@
150	150	u16 off_cntl;
151	151	u32 clcd_cntl;
152	152	u32 cmap[16];
	153	+ bool clk_enabled;
153	154	};
154	155
155	156	static inline void clcdfb_decode(struct clcd_fb fb, struct clcd_regs regs)