Re: [PATCH v3 3/4] dt-bindings: display/msm: Document MDSS on QCS8300

From: Krzysztof Kozlowski <krzk@kernel.org>
To: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Yongxing Mou <quic_yongmou@quicinc.com>,
	Rob Clark <robdclark@gmail.com>,
	Abhinav Kumar <quic_abhinavk@quicinc.com>,
	Sean Paul <sean@poorly.run>,
	Marijn Suijten <marijn.suijten@somainline.org>,
	David Airlie <airlied@gmail.com>, Simona Vetter <simona@ffwll.ch>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Kuogee Hsieh <quic_khsieh@quicinc.com>,
	Vinod Koul <vkoul@kernel.org>,
	Kishon Vijay Abraham I <kishon@kernel.org>,
	Bjorn Andersson <andersson@kernel.org>,
	linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org,
	freedreno@lists.freedesktop.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-phy@lists.infradead.org
Subject: Re: [PATCH v3 3/4] dt-bindings: display/msm: Document MDSS on QCS8300
Date: Tue, 14 Jan 2025 12:19:54 +0100	[thread overview]
Message-ID: <2bafc177-b996-43ae-bd37-f095c9f16b62@kernel.org> (raw)
In-Reply-To: <rx5jyaehsgdw5cluyjtrn5yvxnd2uemdde5jbvq2dq3dirr2ak@hkegxop7tiew>

On 14/01/2025 12:09, Dmitry Baryshkov wrote:
> On Tue, Jan 14, 2025 at 11:11:23AM +0100, Krzysztof Kozlowski wrote:
>> On 14/01/2025 11:00, Dmitry Baryshkov wrote:
>>> On Tue, 14 Jan 2025 at 09:57, Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>>>
>>>> On Mon, Jan 13, 2025 at 04:03:10PM +0800, Yongxing Mou wrote:
>>>>> +patternProperties:
>>>>> +  "^display-controller@[0-9a-f]+$":
>>>>> +    type: object
>>>>> +    additionalProperties: true
>>>>> +
>>>>> +    properties:
>>>>> +      compatible:
>>>>> +        items:
>>>>> +          - const: qcom,qcs8300-dpu
>>>>> +          - const: qcom,sa8775p-dpu
>>>>> +
>>>>> +  "^displayport-controller@[0-9a-f]+$":
>>>>> +    type: object
>>>>> +    additionalProperties: true
>>>>> +
>>>>> +    properties:
>>>>> +      compatible:
>>>>> +        items:
>>>>> +          - const: qcom,qcs8300-dp
>>>>> +          - const: qcom,sm8650-dp
>>>>
>>>> Parts of qcs8300 display are compatible with sa8775p, other parts with
>>>> sm8650. That's odd or even not correct. Assuming it is actually correct,
>>>> it deserves explanation in commit msg.
>>>
>>> It seems to be correct. These are two different IP blocks with
>>> different modifications. QCS8300's DP configuration matches the SM8650
>>> ([1]), though the DPU is the same as the one on the SA8775P platform.
>>>
>>> [1] https://lore.kernel.org/dri-devel/411626da-7563-48fb-ac7c-94f06e73e4b8@quicinc.com/
>>
>> That's the driver, so you claim that qcs8300, which is a sa8775p, is not
>> compatible with sa8775p because of current driver code? You see the
>> contradiction? sa8775p is not compatible with sa8775p because of current
>> driver patch?
> 
> I think you are slightly confused with different similar QCS SKUs here.
> QCS9100 is sa8775p. QCS8300 is a lighter version of it.

True, yet still qcs8300 derives from SA8775p:

https://lore.kernel.org/all/acdf1267-ce56-4ec1-8407-a5f3212a8bfe@quicinc.com/

Therefore my comment, that commit msg must explain why derivative
display is SA8775p-compatible in DPU part, but not in DP part, is still
valid.

Look how useful is commit msg here:

"Document the MDSS hardware found on the Qualcomm QCS8300 platform."

It says exactly what is in the diff. As well we could just skip it...

Best regards,
Krzysztof

-- 
linux-phy mailing list
linux-phy@lists.infradead.org
https://lists.infradead.org/mailman/listinfo/linux-phy