Date: Fri, 19 Apr 2024 09:40:22 +0200
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: chunkuang.hu@...nel.org, robh@...nel.org,
 krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
 p.zabel@...gutronix.de, airlied@...il.com, daniel@...ll.ch,
 maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de,
 matthias.bgg@...il.com, shawn.sung@...iatek.com, yu-chang.lee@...iatek.com,
 ck.hu@...iatek.com, jitao.shi@...iatek.com, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 linux-mediatek@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
 wenst@...omium.org, kernel@...labora.com
Subject: Re: [PATCH v2 1/3] dt-bindings: display: mediatek: Add OF graph
 support for board path

Il 09/04/24 17:45, Dmitry Baryshkov ha scritto:
> On Tue, 9 Apr 2024 at 18:41, AngeloGioacchino Del Regno
> <angelogioacchino.delregno@...labora.com> wrote:
>>
>> Il 09/04/24 17:20, Dmitry Baryshkov ha scritto:
>>> On Tue, Apr 09, 2024 at 02:02:09PM +0200, AngeloGioacchino Del Regno wrote:
>>>> The display IPs in MediaTek SoCs support being interconnected with
>>>> different instances of DDP IPs (for example, merge0 or merge1) and/or
>>>> with different DDP IPs (for example, rdma can be connected with either
>>>> color, dpi, dsi, merge, etc), forming a full Display Data Path that
>>>> ends with an actual display.
>>>>
>>>> The final display pipeline is effectively board specific, as it does
>>>> depend on the display that is attached to it, and eventually on the
>>>> sensors supported by the board (for example, Adaptive Ambient Light
>>>> would need an Ambient Light Sensor, otherwise it's pointless!), other
>>>> than the output type.
>>>
>>> With the color and gamma being in play, should the configuration be
>>> board-driver or rather use-case driven with the driver being able to
>>> reroute some of the blocks at runtime?
>>>
>>
>> The driver can already set some blocks to "BYPASS MODE" at runtime, meaning
>> that those will work as simple pass-through, performing *no* processing at
>> all, so that's addressed from the very beginning.
>>
>> This doesn't mean that a specific pipeline must always support the "DISP_GAMMA"
>> or the "DISP_CCOLOR" block(s) alone, or together, or in combination with another
>> specific block.
> 
> I was thinking about slightly different case: do you have enough
> colour blocks to drive all outputs or do you have to select them for
> the particular output only?

Sorry for the very very very very .. very late reply, your email slipped through
the cracks and I just noticed it.

That depends on the SoC, but generally... no, you have to select them for the
particular output.

There is a restricted set of outputs that support this block, but between this
set, there are still not enough blocks for all of them.

> 
> (excuse me, I didn't check the platform details).

You (and me, and everyone else) can't really invest hours of time to check on
how each and every SoC on the planet works - that's normal.

No worries ;-)

Cheers,
Angelo

> 
>> For any other question, clarification, etc, I'm here :-)
>>
>> Cheers!
>>
>>>>
>>>> Add support for OF graphs to most of the MediaTek DDP (display) bindings
>>>> to add flexibility to build custom hardware paths, hence enabling board
>>>> specific configuration of the display pipeline and allowing to finally
>>>> migrate away from using hardcoded paths.
>>>>
>>>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
>>>
>>
> 
> 

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