linux-kernel - Re: [PATCH 2/3] drm/nouveau/kms/nv50-: Report max cursor size to userspace

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Message-ID: <CAKb7UvjmdgS536tNzisomi_oXOGk3Q+anp0AfPvA8OruU_9m5Q@mail.gmail.com>
Date:   Tue, 23 Feb 2021 13:13:59 -0500
From:   Ilia Mirkin <imirkin@...m.mit.edu>
To:     Alex Riesen <alexander.riesen@...itec.com>
Cc:     Lyude Paul <lyude@...hat.com>,
        Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@...el.com>,
        David Airlie <airlied@...ux.ie>,
        nouveau <nouveau@...ts.freedesktop.org>,
        James Jones <jajones@...dia.com>,
        LKML <linux-kernel@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Jeremy Cline <jcline@...hat.com>,
        Ben Skeggs <bskeggs@...hat.com>,
        Dave Airlie <airlied@...hat.com>
Subject: Re: [PATCH 2/3] drm/nouveau/kms/nv50-: Report max cursor size to userspace

On Tue, Feb 23, 2021 at 11:23 AM Alex Riesen
<alexander.riesen@...itec.com> wrote:
>
> Alex Riesen, Tue, Feb 23, 2021 16:51:26 +0100:
> > Ilia Mirkin, Tue, Feb 23, 2021 16:46:52 +0100:
> > > I'd recommend using xf86-video-nouveau in any case, but some distros
> >
> > I would like try this out. Do you know how to force the xorg server to
> > choose this driver instead of modesetting?
>
> Found that myself (a Device section with Driver set to "nouveau"):
>
>     $ xrandr  --listproviders
>     Providers: number : 1
>     Provider 0: id: 0x68 cap: 0x7, Source Output, Sink Output, Source Offload crtcs: 4 outputs: 5 associated providers: 0 name:nouveau
>
> And yes, the cursor looks good in v5.11 even without reverting the commit.

FWIW it's not immediately apparent to me what grave error modesetting
is committing in setting the cursor. The logic looks perfectly
reasonable. It's not trying to be fancy with rendering the cursor/etc.

The one thing is that it's using drmModeSetCursor2 which sets the
hotspot at the same time. But internally inside nouveau I think it
should work out to the same thing. Perhaps setting the hotspot, or
something in that path, doesn't quite work for 256x256? [Again, no
clue what that might be.]

It might also be worthwhile just testing if the 256x256 cursor works
quite the way one would want. If you're interested, grab libdrm,
there's a test called 'modetest', which has an option to enable a
moving cursor (-c iirc). It's hard-coded to 64x64, so you'll have to
modify it there too (and probably change the pattern from plain gray
to any one of the other ones).

Cheers,

  -ilia