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

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Date:	Tue, 26 Aug 2014 15:37:54 +0300
From:	Tomi Valkeinen <tomi.valkeinen@...com>
To:	Ian Abbott <abbotti@....co.uk>, <linux-fbdev@...r.kernel.org>
CC:	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] video: da8xx-fb: preserve display width when changing
 HSYNC

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@....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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