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>

2 files changed, 9 insertions, 2 deletions

diff --git a/drivers/video/amba-clcd.c b/drivers/video/amba-clcd.c
index afe21e6eb544..1c2c68356ea7 100644
--- 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 ca16c3801a1e..be33b3affc8a 100644
--- 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)