2023-12-15 16:14:46

by Hamza Mahfooz

[permalink] [raw]
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

On 11/14/23 05:55, Mikhail Gavrilov wrote:
> Hi,
> Yesterday came the 6.7-rc1 kernel.
> And surprisingly it turned out it is not working with my LG C3.
> I use this OLED TV as my primary monitor.
> After login to GNOME I see a horizontal flashing bar with a picture of
> the desktop background on white screen.
> Demonstration: https://youtu.be/7F76VfRkrVo
>
> I made a bisection.
> And bisect said that the first bad commit is:
> commit ed6e2782e9747508888f671e1101250bb19045be
> Author: Alvin Lee <[email protected]>
> Date: Mon Oct 23 14:33:16 2023 -0400
>
> drm/amd/display: For cursor P-State allow for SubVP
>
> [Description]
> - Similar to FPO, SubVP should also force cursor P-State
> allow instead of relying on natural assertion
> - Implement code path to force and unforce cursor P-State
> allow for SubVP
>
> Reviewed-by: Samson Tam <[email protected]>
> Acked-by: Hersen Wu <[email protected]>
> Signed-off-by: Alvin Lee <[email protected]>
> Tested-by: Daniel Wheeler <[email protected]>
> Signed-off-by: Alex Deucher <[email protected]>
>
> drivers/gpu/drm/amd/display/dc/hwss/dcn32/dcn32_hwseq.c | 17 ++---------------
> 1 file changed, 2 insertions(+), 15 deletions(-)
>
> My hardware specs: https://linux-hardware.org/?probe=1c989dab38

Can you try the following patch with old fw (version 0x07002100 should
be fine)?: https://patchwork.freedesktop.org/patch/572298/

>
--
Hamza



2023-12-17 21:39:55

by Mikhail Gavrilov

[permalink] [raw]
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

On Fri, Dec 15, 2023 at 9:14 PM Hamza Mahfooz <[email protected]> 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 <[email protected]> on 7900XTX hardware.

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?

--
Best Regards,
Mike Gavrilov.

2023-12-19 17:05:47

by Alex Deucher

[permalink] [raw]
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

On Mon, Dec 18, 2023 at 1:31 PM Mikhail Gavrilov
<[email protected]> wrote:
>
> On Fri, Dec 15, 2023 at 9:14 PM Hamza Mahfooz <[email protected]> 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 <[email protected]> on 7900XTX hardware.
>
> 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