Re: [PATCH AUTOSEL 5.4 006/130] drm/amd/display: Do not silently accept DCC for multiplane formats.

[Kazlauskas, Nicholas]

On 2020-12-29 9:54 a.m., Deucher, Alexander wrote:
> [AMD Public Use]
>
>
> I don't know if these fixes related to modifiers make sense in the 
> pre-modifier code base.  Bas, Nick?
>
> Alex

Mesa should be the only userspace trying to make use of DCC and it 
doesn't do it for video formats. From the kernel side of things we've 
also never supported this and you'd get corruption on the screen if you 
tried.

It's a "fix" for both pre-modifiers and post-modifiers code.

Regards,
Nicholas Kazlauskas

> ------------------------------------------------------------------------
> *From:* amd-gfx <amd-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> on behalf of 
> Sasha Levin <sashal@xxxxxxxxxx>
> *Sent:* Tuesday, December 22, 2020 9:16 PM
> *To:* linux-kernel@xxxxxxxxxxxxxxx <linux-kernel@xxxxxxxxxxxxxxx>; 
> stable@xxxxxxxxxxxxxxx <stable@xxxxxxxxxxxxxxx>
> *Cc:* Sasha Levin <sashal@xxxxxxxxxx>; dri-devel@xxxxxxxxxxxxxxxxxxxxx 
> <dri-devel@xxxxxxxxxxxxxxxxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx 
> <amd-gfx@xxxxxxxxxxxxxxxxxxxxx>; Bas Nieuwenhuizen 
> <bas@xxxxxxxxxxxxxxxxxxx>; Deucher, Alexander 
> <Alexander.Deucher@xxxxxxx>; Kazlauskas, Nicholas 
> <Nicholas.Kazlauskas@xxxxxxx>
> *Subject:* [PATCH AUTOSEL 5.4 006/130] drm/amd/display: Do not silently 
> accept DCC for multiplane formats.
> From: Bas Nieuwenhuizen <bas@xxxxxxxxxxxxxxxxxxx>
>
> [ Upstream commit b35ce7b364ec80b54f48a8fdf9fb74667774d2da ]
>
> Silently accepting it could result in corruption.
>
> Signed-off-by: Bas Nieuwenhuizen <bas@xxxxxxxxxxxxxxxxxxx>
> Reviewed-by: Alex Deucher <alexander.deucher@xxxxxxx>
> Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx>
> Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c 
> b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index d2dd387c95d86..ce70c42a2c3ec 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -2734,7 +2734,7 @@ fill_plane_dcc_attributes(struct amdgpu_device *adev,
>                   return 0;
>
>           if (format >= SURFACE_PIXEL_FORMAT_VIDEO_BEGIN)
> -               return 0;
> +               return -EINVAL;
>
>           if (!dc->cap_funcs.get_dcc_compression_cap)
>                   return -EINVAL;
> --
> 2.27.0
>
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