Message-ID: <CAKMK7uEzoFyW6o1gP6xszWH7fKHrVSR32JLs73KeFfYgD=BHPQ@mail.gmail.com>
Date:   Wed, 1 Jul 2020 18:01:10 +0200
From:   Daniel Vetter <daniel.vetter@...ll.ch>
To:     James Jones <jajones@...dia.com>
Cc:     Karol Herbst <kherbst@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Ben Skeggs <bskeggs@...hat.com>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [git pull] drm for 5.8-rc1

On Wed, Jul 1, 2020 at 5:51 PM James Jones <jajones@...dia.com> wrote:
>
> On 7/1/20 4:24 AM, Karol Herbst wrote:
> > On Wed, Jul 1, 2020 at 6:45 AM James Jones <jajones@...dia.com> wrote:
> >>
> >> This implies something is trying to use one of the old
> >> DRM_FORMAT_MOD_NVIDIA_16BX2_BLOCK format modifiers with DRM-KMS without
> >> first checking whether it is supported by the kernel.  I had tried to
> >> force an Xorg+Mesa stack without my userspace patches to hit this error
> >> when testing, but must have missed some permutation.  If the stalled
> >> Mesa patches go in, this would stop happening of course, but those were
> >> held up for a long time in review, and are now waiting on me to make
> >> some modifications.
> >>
> >
> > that's completely irrelevant. If a kernel change breaks userspace,
> > it's a kernel bug.
>
> Agreed it is unacceptable to break userspace, but I don't think it's
> irrelevant.  Perhaps the musings on pending userspace patches are.
>
> My intent here was to point out it appears at first glance that
> something isn't behaving as expected in userspace, so fixing this would
> likely require some sort of work-around for broken userspace rather than
> straight-forward fixing of a bug in the kernel logic.  My intent was not
> to shift blame to something besides my code & testing for the
> regression, though I certainly see how it could be interpreted that way.
>
> Regardless, I'm looking in to it.

If we do need to have a kernel workaround I'm happy to help out, I've
done a bunch of these and occasionally it's good to get rather
creative :-)

Ideally we'd also push a minimal fix in userspace to all stable
branches and make sure distros upgrade (might need releases if some
distro is stuck on old horrors), so that we don't have to keep the
hack in place for 10+ years or so. Definitely if the hack amounts to
disabling modifiers on nouveau, that would be kinda sad.
-Daniel

>
> Thanks,
> -James
>
> >> Are you using the modesetting driver in X?  If so, with glamor I
> >> presume?  What version of Mesa?  Any distro patches?  Any non-default
> >> xorg.conf options that would affect modesetting, your X driver if it
> >> isn't modesetting, or glamour?
> >>
> >> Thanks,
> >> -James
> >>
> >> On 6/30/20 4:08 PM, Kirill A. Shutemov wrote:
> >>> On Tue, Jun 02, 2020 at 04:06:32PM +1000, Dave Airlie wrote:
> >>>> James Jones (4):
> >>> ...
> >>>>         drm/nouveau/kms: Support NVIDIA format modifiers
> >>>
> >>> This commit is the first one that breaks Xorg startup for my setup:
> >>> GTX 1080 + Dell UP2414Q (4K DP MST monitor).
> >>>
> >>> I believe this is the crucial part of dmesg (full dmesg is attached):
> >>>
> >>> [   29.997140] [drm:nouveau_framebuffer_new] Unsupported modifier: 0x300000000000014
> >>> [   29.997143] [drm:drm_internal_framebuffer_create] could not create framebuffer
> >>> [   29.997145] [drm:drm_ioctl] pid=3393, ret = -22
> >>>
> >>> Any suggestions?
> >>>
> >> _______________________________________________
> >> dri-devel mailing list
> >> dri-devel@...ts.freedesktop.org
> >> https://lists.freedesktop.org/mailman/listinfo/dri-devel
> >>
> >
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@...ts.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> >



--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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