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From: Daniel Vetter <firstname.lastname@example.org>
To: Alex Deucher <email@example.com>
Cc: "Michel Dänzer" <firstname.lastname@example.org>,
"Christian König" <email@example.com>,
"Zhenneng Li" <firstname.lastname@example.org>,
"Alex Deucher" <email@example.com>,
"Pan, Xinhui" <Xinhui.Pan@amd.com>,
"David Airlie" <firstname.lastname@example.org>,
"amd-gfx list" <email@example.com>,
"Maling list - DRI developers" <firstname.lastname@example.org>,
"Daniel Vetter" <email@example.com>
Subject: Re: [PATCH] drm/radeon: Update pitch for page flip
Date: Wed, 4 Aug 2021 17:46:40 +0200 [thread overview]
Message-ID: <YQq2YAi4w79JNO4H@phenom.ffwll.local> (raw)
On Tue, Aug 03, 2021 at 10:49:39AM -0400, Alex Deucher wrote:
> On Tue, Aug 3, 2021 at 4:34 AM Michel Dänzer <firstname.lastname@example.org> wrote:
> > On 2021-08-02 4:51 p.m., Alex Deucher wrote:
> > > On Mon, Aug 2, 2021 at 4:31 AM Daniel Vetter <email@example.com> wrote:
> > >>
> > >> On Mon, Aug 02, 2021 at 10:12:47AM +0200, Christian König wrote:
> > >>> Am 02.08.21 um 09:43 schrieb Zhenneng Li:
> > >>>> When primary bo is updated, crtc's pitch may
> > >>>> have not been updated, this will lead to show
> > >>>> disorder content when user changes display mode,
> > >>>> we update crtc's pitch in page flip to avoid
> > >>>> this bug.
> > >>>> This refers to amdgpu's pageflip.
> > >>>
> > >>> Alex is the expert to ask about that code, but I'm not sure if that is
> > >>> really correct for the old hardware.
> > >>>
> > >>> As far as I know the crtc's pitch should not change during a page flip, but
> > >>> only during a full mode set.
> > >>>
> > >>> So could you elaborate a bit more how you trigger this?
> > >>
> > >> legacy page_flip ioctl only verifies that the fb->format stays the same.
> > >> It doesn't check anything else (afair never has), this is all up to
> > >> drivers to verify.
> > >>
> > >> Personally I'd say add a check to reject this, since testing this and
> > >> making sure it really works everywhere is probably a bit much on this old
> > >> hw.
> > >
> > > If just the pitch changed, that probably wouldn't be much of a
> > > problem, but if the pitch is changing, that probably implies other
> > > stuff has changed as well and we'll just be chasing changes. I agree
> > > it would be best to just reject anything other than updating the
> > > scanout address.
> > FWIW, that means page flipping cannot be used in some cases which work fine by changing the pitch, which can result in tearing: https://gitlab.freedesktop.org/xorg/xserver/-/issues/839 (which says the i915 driver handles this as well).
> Ok. In that case, @Zhenneng can you update all of the pitch in all of
> the page_flip functions in radeon rather than just the evergreen one?
atomic drivers handle this fairly ok-ish, since we have a proper
For legacy kms I just wouldn't bother, too many corners to validate. But
also if you're bored, just do it :-)
> > --
> > Earthling Michel Dänzer | https://redhat.com
> > Libre software enthusiast | Mesa and X developer
Software Engineer, Intel Corporation
prev parent reply other threads:[~2021-08-04 15:46 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-02 7:43 Zhenneng Li
[not found] ` <firstname.lastname@example.org>
2021-08-02 8:31 ` Daniel Vetter
2021-08-02 14:51 ` Alex Deucher
2021-08-03 8:00 ` 李真能
2021-08-03 8:34 ` Michel Dänzer
2021-08-03 14:49 ` Alex Deucher
2021-08-04 15:46 ` Daniel Vetter [this message]
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