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From:   Rob Clark <robdclark@gmail.com>
Date:   Sat, 3 Jul 2021 11:26:59 -0700
Message-ID: <CAF6AEGs6ochnO=CdOk8U9ZFSecv8JSiA=L9es_rcFReJ3Sz7dQ@mail.gmail.com>
Subject: Re: [RFC] Inline rotation support in dpu driver
To:     Kalyan Thota <kalyan_t@codeaurora.org>
Cc:     dri-devel <dri-devel@lists.freedesktop.org>,
        linux-arm-msm <linux-arm-msm@vger.kernel.org>,
        freedreno <freedreno@lists.freedesktop.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Douglas Anderson <dianders@chromium.org>,
        Krishna Manikandan <mkrishn@codeaurora.org>
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On Sat, Jul 3, 2021 at 4:32 AM Kalyan Thota <kalyan_t@codeaurora.org> wrote:
>
> This change adds support for inline rotation in the dpu driver.
> When inline rotation is enabled the VIG pipes will directly fetch the image
> from memory in a rotated fashion
>
> Inline rotation has following restrictions
> 1) Supported only with compressed formats
> 2) max pre rotated height is 1088
> 3) restrictions with downscaling ratio
>
> Queries:
>
> 1) Since inline rotation works for fewer pixel formats with specific modifier, how can we provide this information to the compositor so that
> chrome compositor can choose between overlaying or falling back to GPU. In the patch it fails in the atomic check.
>
> 2) If a display composition fails in atomic check due to any of the restrictions in overlays
> can chrome compositor switch it back to the GPU and re trigger the commit ?

The correct way to provide this information to userspace is for the
atomic test step to fail.  Admittedly the CrOS compositor makes some
invalid assumptions that if a given state was valid in the past, it
will be valid in the future.  But I don't see height/format/downscale
restrictions as a thing that would change from frame to frame.

BR,
-R

> posting it as RFC as validation is not complete, please share early comments on this.
>
> Kalyan Thota (1):
>   drm/msm/disp/dpu1: add support for inline rotation in dpu driver
>
>  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.c | 47 +++++++++----
>  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h | 20 ++++++
>  drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c      | 93 ++++++++++++++++++++------
>  drivers/gpu/drm/msm/disp/dpu1/dpu_plane.h      |  2 +
>  4 files changed, 128 insertions(+), 34 deletions(-)
>
> --
> 2.7.4
>