From: Daniel Vetter <daniel.vetter@ffwll.ch>
To: James Jones <jajones@nvidia.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
Linus Torvalds <torvalds@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
Ben Skeggs <bskeggs@redhat.com>
Subject: Re: [git pull] drm for 5.8-rc1
Date: Thu, 2 Jul 2020 09:36:29 +0200 [thread overview]
Message-ID: <CAKMK7uGJW7S6msS6MzxMAzNoUvfcZbajhc8rhD39d4TUk4Vx8w@mail.gmail.com> (raw)
In-Reply-To: <77e744b9-b5e2-9e9b-44c1-98584d2ae2f3@nvidia.com>
On Wed, Jul 1, 2020 at 9:45 PM James Jones <jajones@nvidia.com> wrote:
>
> OK, I think I see what's going on. In the Xorg modesetting driver, the
> logic is basically:
>
> if (gbm_has_modifiers && DRM_CAP_ADDFB2_MODIFIERS != 0) {
> drmModeAddFB2WithModifiers(..., gbm_bo_get_modifier(bo->gbm));
> } else {
> drmModeAddFB(...);
> }
>
> There's no attempt to verify the DRM-KMS device supports the modifier,
> but then, why would there be? GBM presumably chose a supported modifier
> at buffer creation time, and we don't know which plane the FB is going
> to be used with yet. GBM doesn't actually ask the kernel which
> modifiers it supports here either though. It just goes into Mesa via
> DRI and reports the modifier (unpatched) Mesa chose on its own. Mesa
> just hard-codes the modifiers in its driver backends since its thinking
> in terms of a device's 3D engine, not display. In theory, Mesa's DRI
> drivers could query KMS for supported modifiers if allocating from GBM
> using the non-modifiers path and the SCANOUT flag is set (perhaps some
> drivers do this or its equivalent? Haven't checked.), but that seems
> pretty gnarly and doesn't fix the modifier-based GBM allocation path
> AFAIK. Bit of a mess.
>
> For a quick userspace fix that could probably be pushed out everywhere
> (Only affects Xorg server 1.20+ AFAIK), just retrying
> drmModeAddFB2WithModifiers() without the DRM_MODE_FB_MODIFIERS flag on
> failure should be sufficient. Still need to verify as I'm having
> trouble wrangling my Xorg build at the moment and I'm pressed for time.
> A more complete fix would be quite involved, as modesetting isn't really
> properly plumbed to validate GBM's modifiers against KMS planes, and it
> doesn't seem like GBM/Mesa/DRI should be responsible for this as noted
> above given the general modifier workflow/design.
>
> Most importantly, options I've considered for fixing from the kernel side:
>
> -Accept "legacy" modifiers in nouveau in addition to the new modifiers,
> though avoid reporting them to userspace as supported to avoid further
> proliferation. This is pretty straightforward. I'll need to modify
> both the AddFB2 handler (nouveau_validate_decode_mod) and the mode set
> plane validation logic (nv50_plane_format_mod_supported), but it should
> end up just being a few lines of code.
>
> -Don't validate modifiers in AddFB. This doesn't really gain anything
> because it just pushes the failure down to mode set time, so it's not
> that useful, so I don't plan on pursuing this.
>
> As noted, need to run just now, but I should have a kernel patch to test
> out either tonight or tomorrow.
>
> If anyone's curious, the reason my testing missed this was I did most of
> my verification of "old" code against the Xorg 1.19 build included with
> my distro. I did hack up a Xorg 1.20-ish build to test as well that
> would have included this path, but I must not have properly configured
> it with GBM modifier support somehow. I was pretty focused on just
> testing the forcibly-disabled atomic path in the modesetting driver in
> this build, so I didn't look too closely at things beyond that.
Yeah, so modifier support in -modesetting is totally broken. It should
be disabled by default because the stuff just doesn't really work.
If that doesn't help then I guess we need to do the same thing as what
we've done for atomic already in:
commit 26b1d3b527e7bf3e24b814d617866ac5199ce68d
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Thu Sep 5 20:53:18 2019 +0200
drm/atomic: Take the atomic toys away from X
For added insult for the atomic stuff: Xorg master branch is actually
fixed, but no one has done a release of that in over 2 years, so the
fixes never got anywhere. I have little hope the Xorg will get back
into shape, seems abandoned unfortunately.
-Daniel
>
> Thanks,
> -James
>
> On 7/1/20 12:59 AM, Kirill A. Shutemov wrote:
> > On Wed, Jul 01, 2020 at 10:57:19AM +0300, Kirill A. Shutemov wrote:
> >> On Tue, Jun 30, 2020 at 09:40:19PM -0700, James Jones 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.
> >>>
> >>> Are you using the modesetting driver in X? If so, with glamor I presume?
> >>
> >> Yes and yes. I attached Xorg.log.
> >
> > Attached now.
> >
> >
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> >
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2020-07-02 7:36 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-02 6:06 [git pull] drm for 5.8-rc1 Dave Airlie
2020-06-02 21:21 ` Linus Torvalds
2020-06-02 21:22 ` Linus Torvalds
2020-06-02 21:56 ` Linus Torvalds
2020-06-03 7:18 ` Thomas Zimmermann
2020-06-03 7:43 ` Daniel Vetter
2020-06-02 22:14 ` Linus Torvalds
2020-06-02 23:03 ` Dave Airlie
2020-06-02 22:20 ` pr-tracker-bot
2020-06-03 20:13 ` Jason Gunthorpe
2020-06-04 8:10 ` Christian König
2020-06-30 23:08 ` Kirill A. Shutemov
2020-07-01 4:40 ` James Jones
2020-07-01 7:57 ` Kirill A. Shutemov
2020-07-01 7:59 ` Kirill A. Shutemov
2020-07-01 19:45 ` James Jones
2020-07-02 7:36 ` Daniel Vetter [this message]
2020-07-02 7:59 ` Pekka Paalanen
2020-07-02 8:22 ` Daniel Stone
2020-07-02 21:14 ` James Jones
2020-07-03 6:01 ` James Jones
2020-07-03 7:16 ` Daniel Vetter
2020-07-13 1:37 ` Dave Airlie
2020-07-14 14:31 ` James Jones
2020-08-04 8:58 ` Karol Herbst
2020-08-12 0:19 ` James Jones
2020-08-12 10:27 ` Karol Herbst
2020-08-12 10:43 ` Karol Herbst
2020-08-12 12:24 ` Karol Herbst
2020-08-12 12:37 ` Ilia Mirkin
2020-08-12 17:03 ` James Jones
2020-08-12 17:10 ` Karol Herbst
2020-08-12 17:19 ` James Jones
2020-08-12 17:40 ` Alyssa Rosenzweig
2020-08-12 18:24 ` James Jones
2020-08-12 18:51 ` Karol Herbst
2020-08-13 13:00 ` Karol Herbst
2020-08-13 15:39 ` Karol Herbst
2020-08-13 17:19 ` Karol Herbst
2020-08-13 17:45 ` James Jones
2020-08-13 17:48 ` Karol Herbst
2020-08-14 13:57 ` Thierry Reding
2020-08-14 13:59 ` Karol Herbst
2020-08-14 14:10 ` Thierry Reding
2020-08-14 14:05 ` Thierry Reding
2020-08-14 14:44 ` Karol Herbst
2020-08-14 15:34 ` Thierry Reding
2020-08-14 15:40 ` Karol Herbst
2020-08-14 16:06 ` Thierry Reding
2020-08-14 16:12 ` Karol Herbst
2020-08-14 16:22 ` Thierry Reding
2020-08-14 17:17 ` Daniel Stone
2020-08-14 17:25 ` Daniel Vetter
2020-08-18 14:37 ` Thierry Reding
2020-09-01 7:13 ` Daniel Vetter
2020-09-01 10:42 ` Daniel Stone
2020-09-01 10:59 ` Karol Herbst
2020-09-01 14:42 ` James Jones
2020-08-14 14:08 ` Thierry Reding
2020-08-14 14:45 ` Karol Herbst
2020-08-14 15:24 ` Thierry Reding
2020-08-14 15:43 ` Karol Herbst
2020-08-14 13:54 ` Thierry Reding
2020-08-14 13:40 ` Thierry Reding
2020-08-14 13:56 ` Karol Herbst
2020-08-12 15:05 ` Thierry Reding
2020-08-12 15:20 ` Karol Herbst
2020-08-12 15:49 ` Karol Herbst
2020-07-01 11:24 ` Karol Herbst
2020-07-01 15:51 ` James Jones
2020-07-01 16:01 ` Daniel Vetter
2020-07-01 17:04 ` Karol Herbst
2020-07-01 17:37 ` James Jones
2020-07-01 18:08 ` Karol Herbst
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAKMK7uGJW7S6msS6MzxMAzNoUvfcZbajhc8rhD39d4TUk4Vx8w@mail.gmail.com \
--to=daniel.vetter@ffwll.ch \
--cc=bskeggs@redhat.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=jajones@nvidia.com \
--cc=kirill@shutemov.name \
--cc=linux-kernel@vger.kernel.org \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).