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>

diff --git a/drivers/video/amba-clcd.c b/drivers/video/amba-clcd.c
index afe21e6..1c2c683 100644 (file)
--- a/drivers/video/amba-clcd.c
+++ b/drivers/video/amba-clcd.c
@@ -80,7 +80,10 @@ static void clcdfb_disable(struct clcd_fb *fb)
        /*
         * 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 @@ static void clcdfb_enable(struct clcd_fb *fb, u32 cntl)
        /*
         * 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..

diff --git a/include/linux/amba/clcd.h b/include/linux/amba/clcd.h
index ca16c38..be33b3a 100644 (file)
--- a/include/linux/amba/clcd.h
+++ b/include/linux/amba/clcd.h
@@ -150,6 +150,7 @@ struct clcd_fb {
        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)