linux-kernel - Re: [PATCH 3/3] drm/panfrost: Clamp lock region to Bifrost minimum

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Message-ID: <YSQPiQX8IOkJJSoY@maud>
Date:   Mon, 23 Aug 2021 17:13:45 -0400
From:   Alyssa Rosenzweig <alyssa@...labora.com>
To:     Steven Price <steven.price@....com>
Cc:     Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>,
        dri-devel@...ts.freedesktop.org, Rob Herring <robh@...nel.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, linux-kernel@...r.kernel.org,
        Chris Morgan <macromorgan@...mail.com>, stable@...r.kernel.org
Subject: Re: [PATCH 3/3] drm/panfrost: Clamp lock region to Bifrost minimum

> > When locking a region, we currently clamp to a PAGE_SIZE as the minimum
> > lock region. While this is valid for Midgard, it is invalid for Bifrost,
> 
> While the spec does seem to state it's invalid for Bifrost - kbase
> didn't bother with a lower clamp for a long time. I actually think this
> is in many ways more of a spec bug: i.e. implementation details of the
> round-up that the hardware does. But it's much safer following the spec
> ;) And it seems like kbase eventually caught up too.

Yeah, makes sense. Should I drop the Cc: stable in that case? If the
issue is purely theoretical.