linux-kernel - Re: [PATCH 2/3] drm/nouveau/disp: Always accept linear modifier

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Message-ID: <69bd369e-ceae-490f-8f14-28a2a8e874bc@nvidia.com>
Date: Fri, 22 Aug 2025 14:11:46 -0700
From: James Jones <jajones@...dia.com>
To: Danilo Krummrich <dakr@...nel.org>
Cc: Lyude Paul <lyude@...hat.com>,
 Faith Ekstrand <faith.ekstrand@...labora.com>,
 nouveau@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>, Joel Fernandes <joelagnelf@...dia.com>
Subject: Re: [PATCH 2/3] drm/nouveau/disp: Always accept linear modifier

On 8/22/25 13:55, Danilo Krummrich wrote:
> On Tue Aug 12, 2025 at 12:00 AM CEST, James Jones wrote:
>> On some chipsets, which block-linear modifiers are
>> supported is format-specific. However, linear
>> modifiers are always be supported. The prior
>> modifier filtering logic was not accounting for
>> the linear case.
>>
>> Fixes: c586f30bf74c ("drm/nouveau/kms: Add format mod prop to base/ovly/nvdisp")
>> Signed-off-by: James Jones <jajones@...dia.com>
> 
> This issue seems to be present since v5.10, what's the implication of this? I
> assume this has to be backported into stable releases?
> 
> Does the subsequent patch break strictly depend on this fix, or can it go
> separately?

Without this fix, the next patch breaks linear modifier use on 
Blackwell2+. In my testing, that meant fbcon was severely corrupted (In 
a manner that suggests it ends up with a block-linear surface rendered 
to as if it was linear).

Yes, it has to go back to a fair number of stable branches to fix 
similar issues on pre-fermi GPUs, though oddly in my testing 
before/after this patch, fbcon came up fine on my NV50, so the effects 
might not be as severe there for some reason.

Thanks,
-James