Re: [PATCH/RFC v2] video: fbdev: atari: Fix TT High video mode

[Sam Ravnborg <sam@ravnborg.org>]

Hi Geert.

On Sun, Nov 01, 2020 at 11:29:41AM +0100, Geert Uytterhoeven wrote:
> The horizontal resolution (640) for the TT High video mode (1280x960) is
> definitely bogus.  While fixing that, correct the timings to match the
> TTM195 service manual.
> 
> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
> ---
> Untested on actual hardware, hence the RFC.
> 
> v2:
>   - Use correct base.
> ---
>  drivers/video/fbdev/atafb.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/video/fbdev/atafb.c b/drivers/video/fbdev/atafb.c
> index f253daa05d9d3872..5ecf3ec9f94cb720 100644
> --- a/drivers/video/fbdev/atafb.c
> +++ b/drivers/video/fbdev/atafb.c
> @@ -495,8 +495,8 @@ static struct fb_videomode atafb_modedb[] __initdata = {
>  		"tt-mid", 60, 640, 480, 31041, 120, 100, 8, 16, 140, 30,
>  		0, FB_VMODE_NONINTERLACED | FB_VMODE_YWRAP
>  	}, {
> -		/* 1280x960, 29 kHz, 60 Hz (TT high) */
> -		"tt-high", 57, 640, 960, 31041, 120, 100, 8, 16, 140, 30,
> +		/* 1280x960, 72 kHz, 72 Hz (TT high) */
> +		"tt-high", 57, 1280, 960, 7761, 260, 60, 36, 4, 192, 4,
>  		0, FB_VMODE_NONINTERLACED | FB_VMODE_YWRAP

Well-spotted. The change of 640 => 1280 is surely right.
I have a harder time understanding why the change of pixclock from 31041
to 7761 is correct. All other modes have a pixclock close to or equal
to 32000 - so it looks strange this one is off.

You know a tons more about all this than I do so it is properly right
but I was left wondering so please enlighten me.

	Sam