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From:   Eric Anholt <eric@anholt.net>
To:     Rob Herring <robh+dt@kernel.org>
Cc:     dri-devel <dri-devel@lists.freedesktop.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Ray Jui <rjui@broadcom.com>,
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Subject: Re: [PATCH v3 1/3] drm/vc4: Remove the need for the GPU-subsystem DT node.
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Date:   Tue, 17 Apr 2018 14:48:17 -0700
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Rob Herring <robh+dt@kernel.org> writes:

> On Mon, Apr 16, 2018 at 5:52 PM, Eric Anholt <eric@anholt.net> wrote:
>> The GPU subsystem node was a workaround to have a central device to
>> bind V3D and display to.  Following the lead of 246774d17fc0
>> ("drm/etnaviv: remove the need for a gpu-subsystem DT node"), remove
>> the subsystem node usage and just create a platform device for the DRM
>> device to attach to if any of the subsystem devices are present.
>>
>> v2: Simplify the DT walking code.
>> v3: Always put the node.
>>
>> Signed-off-by: Eric Anholt <eric@anholt.net>
>> ---
>>  .../bindings/display/brcm,bcm-vc4.txt         |  7 -----
>>  drivers/gpu/drm/vc4/vc4_drv.c                 | 28 +++++++++++++------
>>  drivers/gpu/drm/vc4/vc4_hvs.c                 |  1 +
>>  drivers/gpu/drm/vc4/vc4_v3d.c                 |  1 +
>>  4 files changed, 22 insertions(+), 15 deletions(-)
>
> Reviewed-by: Rob Herring <robh@kernel.org>

Unfortunately, on further testing, this ends up broken.  My guess is
that our new platform device isn't on the same bus, so we don't get our
dma-ranges translation when we use drm->dev, and that breaks caching
behavior.

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