[PATCH] video: da8xx-fb: preserve display width when changing HSYNC

[PATCH] video: da8xx-fb: preserve display width when changing HSYNC

[Ian Abbott]

When looking at this driver for a client, I noticed the code that
configures the HSYNC pulse clobbers the display width in the same
register.  It only preserves the MS part of the width in bit 3 and zeros
the LS part of the width in bits 9 to 4.  This doesn't matter during
initialization as the width is configured afterwards, but subsequent use
of the FBIPUT_HSYNC ioctl would clobber the width.

Preserve bits 9 to 0 of LCD_RASTER_TIMING_0_REG when configuring the
horizontal sync.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
---
I haven't tested this change, but it's pretty trivial.
---
 drivers/video/fbdev/da8xx-fb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/da8xx-fb.c b/drivers/video/fbdev/da8xx-fb.c
index 788f6b3..10c876c 100644
--- a/drivers/video/fbdev/da8xx-fb.c
+++ b/drivers/video/fbdev/da8xx-fb.c
@@ -419,7 +419,7 @@ static void lcd_cfg_horizontal_sync(int back_porch, int pulse_width,
 {
 	u32 reg;
 
-	reg = lcdc_read(LCD_RASTER_TIMING_0_REG) & 0xf;
+	reg = lcdc_read(LCD_RASTER_TIMING_0_REG) & 0x3ff;
 	reg |= (((back_porch-1) & 0xff) << 24)
 	    | (((front_porch-1) & 0xff) << 16)
 	    | (((pulse_width-1) & 0x3f) << 10);
-- 
2.0.0

Re: [PATCH] video: da8xx-fb: preserve display width when changing HSYNC

[Tomi Valkeinen]

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On 03/07/14 16:46, Ian Abbott wrote:
> When looking at this driver for a client, I noticed the code that
> configures the HSYNC pulse clobbers the display width in the same
> register.  It only preserves the MS part of the width in bit 3 and zeros
> the LS part of the width in bits 9 to 4.  This doesn't matter during
> initialization as the width is configured afterwards, but subsequent use
> of the FBIPUT_HSYNC ioctl would clobber the width.
> 
> Preserve bits 9 to 0 of LCD_RASTER_TIMING_0_REG when configuring the
> horizontal sync.
> 
> Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
> ---
> I haven't tested this change, but it's pretty trivial.
> ---
>  drivers/video/fbdev/da8xx-fb.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/video/fbdev/da8xx-fb.c b/drivers/video/fbdev/da8xx-fb.c
> index 788f6b3..10c876c 100644
> --- a/drivers/video/fbdev/da8xx-fb.c
> +++ b/drivers/video/fbdev/da8xx-fb.c
> @@ -419,7 +419,7 @@ static void lcd_cfg_horizontal_sync(int back_porch, int pulse_width,
>  {
>  	u32 reg;
>  
> -	reg = lcdc_read(LCD_RASTER_TIMING_0_REG) & 0xf;
> +	reg = lcdc_read(LCD_RASTER_TIMING_0_REG) & 0x3ff;
>  	reg |= (((back_porch-1) & 0xff) << 24)
>  	    | (((front_porch-1) & 0xff) << 16)
>  	    | (((pulse_width-1) & 0x3f) << 10);
> 

Thanks, queued for 3.17 fixes.

 Tomi



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