Re: [PATCH v5 0/7] drm/mgag200: Implement VBLANK support

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Oct 04, 2024 at 11:17:02AM +0200, Thomas Zimmermann wrote:
> Hi
> 
> Am 02.10.24 um 18:15 schrieb Luck, Tony:
> >> Thanks for the bug report. Can you provide the output of 'sudo lspci
> >> -vvv' for the graphics device?
> > Thomas,
> >
> > Sure. Here's the output (run on the v6.11.0 kernel)
> 
> Thanks. It doesn't look much different from other systems. IRQ is also 
> assigned.
> 
> Attached is a patch that fixes a possible off-by-one error in the 
> register settings. This would affect the bug you're reporting. If 
> possible, please apply the patch to your 6.12-rc1, test and report the 
> result.

Didn't one of these weird variants have some bug where the
CRTC startadd was not working? Is this one of those?
That to me sounds like maybe linecomp has internally been
tied to be always active somehow. Perhaps that would
also prevent it from generating the interrupt...

Anyways, sounds like someone should just double check whether
the status bit ever get asserted or not. If yes, then the
problem must be with interrupt delivery, otherwise the
problem is that the internal interrupt is never even
generated. In the latter case you could try using the
vsync interrupt instead.

-- 
Ville Syrjälä
Intel