Wrong vsync offset calculation in drm_edid.c

[Paul Menzel]

Dear Peter,


thank you for your patch. It has some formal issues though.


Am Donnerstag, den 07.03.2013, 16:41 +0100 schrieb Peter Blum:


1. Your subject line does not contain the tag [PATCH].
2. You should CC the maintainers.

> This patch is a bug fix for the file drm_edid.c of the kernel 3.8.

Is that bug also present in Linux 3.9 (Linus’ master branch), which is
the current development branch. Patches have to be submitted against
that branch.

> The vsync offset is calculated wrong from the EDID set because of the

s,wrong,incorrectly,

> wrong shift direction.
> We could measure the bad old setting and also the good new setting after 
> the bug fix.
> 
> 
> Signed-off-by: Peter Blum <Peter.Blum at lxco.com>
> 
> 
> diff -Naur a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> --- a/drivers/gpu/drm/drm_edid.c        2013-02-19 00:58:34.000000000 +0100
> +++ b/drivers/gpu/drm/drm_edid.c        2013-03-07 12:04:24.527609783 +0100
> @@ -893,7 +893,7 @@
>          unsigned vblank = (pt->vactive_vblank_hi & 0xf) << 8 | 
> pt->vblank_lo;

3. Your MUA Thunderbird mangled the patch by automatically breaking
lines. You should disable that or use `git send-email`.

>          unsigned hsync_offset = (pt->hsync_vsync_offset_pulse_width_hi 
> & 0xc0) << 2 | pt->hsync_offset_lo;
>          unsigned hsync_pulse_width = 
> (pt->hsync_vsync_offset_pulse_width_hi & 0x30) << 4 | 
> pt->hsync_pulse_width_lo;
> -       unsigned vsync_offset = (pt->hsync_vsync_offset_pulse_width_hi & 
> 0xc) >> 2 | pt->vsync_offset_pulse_width_lo >> 4;
> +       unsigned vsync_offset = (pt->hsync_vsync_offset_pulse_width_hi & 
> 0xc) << 2 | pt->vsync_offset_pulse_width_lo >> 4;

Not sure where it is determined how to shift that. But if it works for
you, good.

>          unsigned vsync_pulse_width = 
> (pt->hsync_vsync_offset_pulse_width_hi & 0x3) << 4 | 
> (pt->vsync_offset_pulse_width_lo & 0xf);
> 
>          /* ignore tiny modes */

Please send a [PATCH v2] with a comment, what changed in v2 after `---`
right before the diff line.

    $ git commit --amend # to edit commit message
    $ git format-patch -1 --subject-prefix="PATCH v2"


Thanks,

Paul
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