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From: Alex Deucher <alexdeucher@gmail.com>
Date: Tue, 19 Dec 2023 12:01:11 -0500
Message-ID: <CADnq5_Nj3pP4MNnGz+WZZFOtWrXE5-jYQsbkHyCkxWYV-HJrCw@mail.gmail.com>
Subject: Re: regression/bisected/6.7rc1: Instead of desktop I see a horizontal
 flashing bar with a picture of the desktop background on white screen
To: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Cc: Hamza Mahfooz <hamza.mahfooz@amd.com>, 
	Linux List Kernel Mailing <linux-kernel@vger.kernel.org>, amd-gfx list <amd-gfx@lists.freedesktop.org>, 
	daniel.wheeler@amd.com, hersenxs.wu@amd.com, alvin.lee2@amd.com, 
	"Deucher, Alexander" <alexander.deucher@amd.com>
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On Mon, Dec 18, 2023 at 1:31=E2=80=AFPM Mikhail Gavrilov
<mikhail.v.gavrilov@gmail.com> wrote:
>
> On Fri, Dec 15, 2023 at 9:14=E2=80=AFPM Hamza Mahfooz <hamza.mahfooz@amd.=
com> wrote:
> >
> > Can you try the following patch with old fw (version 0x07002100 should
> > be fine)?: https://patchwork.freedesktop.org/patch/572298/
> >
>
> Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com> on 7900XTX har=
dware.
>
> Can I ask?
> What does SubVP actually do?
> I read on Phoronix that this is new feature of DCN 3.2 hardware
> https://www.phoronix.com/news/AMDGPU-Linux-6.5-Improvements
> But I didn't notice that anything began to work better after enabling
> this feature.
> On the contrary, my kernel logs began to become overgrown with
> unpleasant errors.
> See here: https://gitlab.freedesktop.org/drm/amd/-/issues/2796
> I bisected this issue and bisect heads me to commit
> 299004271cbf0315da327c4bd67aec3e7041cb32 which enables SubVP high
> refresh rate.
> But without SubVP I also had 120Hz and 4K. So I ask again what is the
> profit of SubVP?

IIRC, SubVP is a power saving feature which allows us to dynamically
adjust the memory clocks in more cases with narrow blanking periods.

Alex