Re: [PATCH] drm/nouveau: fix duplication of nv50_head_atom struct

[Peteris Rudzusiks <peteris.rudzusiks-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Wed, May 15, 2019 at 11:29:40PM -0400, Ilia Mirkin wrote:
> On Tue, May 14, 2019 at 3:57 PM Peteris Rudzusiks
> <peteris.rudzusiks@gmail.com> wrote:
> >
> > On Tue, May 14, 2019 at 04:55:05PM +1000, Ben Skeggs wrote:
> > > On Sun, 12 May 2019 at 04:23, Peteris Rudzusiks
> > > <peteris.rudzusiks@gmail.com> wrote:
> > > >
> > > > nv50_head_atomic_duplicate_state() makes a copy of nv50_head_atom
> > > > struct. This patch adds copying of struct member named "or", which
> > > > previously was left uninitialized in the duplicated structure.
> > > >
> > > > Due to this bug, incorrect nhsync and nvsync values were sometimes used.
> > > > In my particular case, that lead to a mismatch between the output
> > > > resolution of the graphics device (GeForce GT 630 OEM) and the reported
> > > > input signal resolution on the display. xrandr reported 1680x1050, but
> > > > the display reported 1280x1024. As a result of this mismatch, the output
> > > > on the display looked like it was cropped (only part of the output was
> > > > actually visible on the display).
> > > >
> > > > git bisect pointed to commit 2ca7fb5c1cc6 ("drm/nouveau/kms/nv50: handle
> > > > SetControlOutputResource from head"), which added the member "or" to
> > > > nv50_head_atom structure, but forgot to copy it in
> > > > nv50_head_atomic_duplicate_state().
> > > >
> > > > Fixes: 2ca7fb5c1cc6 ("drm/nouveau/kms/nv50: handle SetControlOutputResource from head")
> > > > Signed-off-by: Peteris Rudzusiks <peteris.rudzusiks@gmail.com>
> > > Oops, nice catch.  Thank you for this, I've merged it in my tree and
> > > will get it upstream ASAP.
> > >
> > > Thanks,
> > > Ben.
> > >
> > Hi Ben,
> >
> > Thank you for taking the time to review and merge this patch.
> >
> > I'm new to the Linux kernel development process, so I am not sure what
> > happens next. Does inclusion in your tree imply that this fix will end
> > up in some (most likely - next) mainline kernel? Will it also be
> > backported to 4.19 LTS branch?
> >
> > This bug affects all kernel versions starting from v4.18. Probably not
> > that many systems though.
> 
> Ben submits a pull request to Dave Airlie (drm maintainer), and Dave
> submits one to Linus for inclusion in the "official" upstream
> repository. Dave just sent a pull request to Linus, who usually picks
> these up within a few days (exceptions apply).
> 
> Once in the mainline tree, the "Fixes" tag is likely to cause it to
> get picked up for stable. You can also nominate it for stable kernel
> branch inclusion explicitly (there are instructions somewhere, but
> basically you send an email to some list saying "please include commit
> ABC in kernels XYZ").
> 
> What Ubuntu ships is, ultimately, up to Ubuntu. They will, however,
> frequently follow the stable kernel branches, and listen to the list
> above as well.
> 
> Hope this helps,
> 
>   -ilia

Thanks for explaing this. I'll wait and see if this patch gets included
in stable releases without explicitly asking for it.

Regards,
Peteris
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