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From:   Alex Deucher <alexdeucher@gmail.com>
Date:   Mon, 10 Jan 2022 17:13:04 -0500
Message-ID: <CADnq5_P9n39RQ5+Nm8O=YKXXvXh1CEzwC2fOEzEJuS2zQLUWEw@mail.gmail.com>
Subject: Re: [git pull] drm for 5.17-rc1 (pre-merge window pull)
To:     Daniel Vetter <daniel.vetter@ffwll.ch>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        "Wentland, Harry" <harry.wentland@amd.com>,
        Dave Airlie <airlied@gmail.com>,
        "Koenig, Christian" <christian.koenig@amd.com>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>,
        amd-gfx list <amd-gfx@lists.freedesktop.org>
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On Mon, Jan 10, 2022 at 5:05 PM Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
>
> On Mon, Jan 10, 2022 at 10:30 PM Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > On Thu, Jan 6, 2022 at 10:12 PM Dave Airlie <airlied@gmail.com> wrote:
> > >
> > >   git://anongit.freedesktop.org/drm/drm tags/drm-next-2022-01-07
> >
> > Gaah. I merged things and it built cleanly, and I pushed it out.
> >
> > But then I actually *booted* it, and that's not pretty.
> >
> > It *works", but it's almost unusable because of random scanline
> > flickering.  I'm not sure how to explain it, but it's as if there
> > wasn't quite enough bandwidth on the scan-out, so you get these lines
> > of noise and/or shifted output. They are temporary - so the
> > framebuffer contents themselves is not damaged (although I don't know
> > how the compositor works - maybe the problem happens before scanout).
> >
> > This is on the same Radeon device:
> >
> >    49:00.0 VGA compatible controller: Advanced Micro Devices, Inc.
> > [AMD/ATI] Ellesmere [Radeon RX 470/480/570/570X/580/580X/590] (rev e7)
> >
> > with dual 4k monitors.
> >
> > Any idea?

Sounds like something related to watermarks.  That said, we haven't
really touched the display code for DCE11 cards in quite a while.  Can
you provide your dmesg output?

Alex


>
> Since Christian is mostly the compute/memory side, adding some display
> folks for this.
> -Daniel
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch