[PATCH] efifb: BGRT: Improve efifb_bgrt_sanity_check

[Hans de Goede]

Hi,

On 21-07-19 15:19, Hans de Goede wrote:
> For various reasons, at least with x86 EFI firmwares, the xoffset and
> yoffset in the BGRT info are not always reliable.
> 
> Extensive testing has shown that when the info is correct, the
> BGRT image is always exactly centered horizontally (the yoffset variable
> is more variable and not always predictable).
> 
> This commit simplifies / improves the bgrt_sanity_check to simply
> check that the BGRT image is exactly centered horizontally and skips
> (re)drawing it when it is not.
> 
> This fixes the BGRT image sometimes being drawn in the wrong place.
> 
> Cc: stable at vger.kernel.org
> Fixes: 88fe4ceb2447 ("efifb: BGRT: Do not copy the boot graphics for non native resolutions")
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>

ping? I do not see this one in -next yet, what is the status of this
patch?

Regards,

Hans




> ---
>   drivers/video/fbdev/efifb.c | 27 ++++++---------------------
>   1 file changed, 6 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c
> index dfa8dd47d19d..5b3cef9bf794 100644
> --- a/drivers/video/fbdev/efifb.c
> +++ b/drivers/video/fbdev/efifb.c
> @@ -122,28 +122,13 @@ static void efifb_copy_bmp(u8 *src, u32 *dst, int width, struct screen_info *si)
>    */
>   static bool efifb_bgrt_sanity_check(struct screen_info *si, u32 bmp_width)
>   {
> -	static const int default_resolutions[][2] = {
> -		{  800,  600 },
> -		{ 1024,  768 },
> -		{ 1280, 1024 },
> -	};
> -	u32 i, right_margin;
> -
> -	for (i = 0; i < ARRAY_SIZE(default_resolutions); i++) {
> -		if (default_resolutions[i][0] == si->lfb_width &&
> -		    default_resolutions[i][1] == si->lfb_height)
> -			break;
> -	}
> -	/* If not a default resolution used for textmode, this should be fine */
> -	if (i >= ARRAY_SIZE(default_resolutions))
> -		return true;
> -
> -	/* If the right margin is 5 times smaller then the left one, reject */
> -	right_margin = si->lfb_width - (bgrt_tab.image_offset_x + bmp_width);
> -	if (right_margin < (bgrt_tab.image_offset_x / 5))
> -		return false;
> +	/*
> +	 * All x86 firmwares horizontally center the image (the yoffset
> +	 * calculations differ between boards, but xoffset is predictable).
> +	 */
> +	u32 expected_xoffset = (si->lfb_width - bmp_width) / 2;
>   
> -	return true;
> +	return bgrt_tab.image_offset_x == expected_xoffset;
>   }
>   #else
>   static bool efifb_bgrt_sanity_check(struct screen_info *si, u32 bmp_width)
>