linux-kernel - Re: [PATCH v8 0/3] media: venus: enable venus on qcs615

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Message-ID: <946e3208-4783-464a-af58-68c4f79d327c@oss.qualcomm.com>
Date: Wed, 11 Jun 2025 17:06:07 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Krzysztof Kozlowski <krzk@...nel.org>,
        Renjiang Han <quic_renjiang@...cinc.com>,
        Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
        Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Vikash Garodia <quic_vgarodia@...cinc.com>,
        Dikshita Agarwal <quic_dikshita@...cinc.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
 <conor+dt@...nel.org>, linux-media@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org,
        Nicolas Dufresne <nicolas.dufresne@...labora.com>
Subject: Re: [PATCH v8 0/3] media: venus: enable venus on qcs615

On 6/7/25 11:46 AM, Krzysztof Kozlowski wrote:
> On 06/06/2025 15:32, Renjiang Han wrote:
>>
>> On 6/6/2025 8:56 PM, Krzysztof Kozlowski wrote:
>>> On 06/06/2025 14:51, Renjiang Han wrote:
>>>> On 6/6/2025 8:44 PM, Krzysztof Kozlowski wrote:
>>>>> On 06/06/2025 14:37, Renjiang Han wrote:
>>>>>> On 6/5/2025 8:34 PM, Bryan O'Donoghue wrote:
>>>>>>> On 31/05/2025 01:05, Renjiang Han wrote:
>>>>>>>>>> Note:
>>>>>>>>>> This series consist of DT patches and a venus driver patch. The patch
>>>>>>>>>> 1/3, which is venus driver patch, can be picked independently without
>>>>>>>>>> having any functional dependency. But patch 2/3 & patch 3/3, which are
>>>>>>>>>> DT patches, still depend on [1].
>>>>>>>>> I'd say 2/3 and 3/3 still depend on 1/3, otherwise we can get video
>>>>>>>>> core
>>>>>>>>> on QCS615 over(?)clocked.
>>>>>>>> Agree, so we need to make sure that the driver patch is not picked
>>>>>>>> after the DT patch.
>>>>>>> This statement is confusing.
>>>>>>>
>>>>>>> 1/3 states that there will be a fallback if there is no OPP table
>>>>>>> present.
>>>>>>>
>>>>>>> Giving the code a glance, I believe that is so, freq_table should be
>>>>>>> used if there is no OPP specified in the DT.
>>>>>>>
>>>>>>> I think we are having a hard time here understanding what you are saying.
>>>>>>>
>>>>>>> My understanding:
>>>>>>>
>>>>>>> - venus modification is standalone 1/3
>>>>>>>     Qcs615 will fallback if no OPP is present
>>>>>>>
>>>>>>> - dt modification 2/3 3/3 is therefore also independent of driver
>>>>>>>
>>>>>>> ---
>>>>>>> bod
>>>>>> yes, let me re-spin this with driver patch alone. Once that gets in,
>>>>>> will bring in the DT patches.
>>>>> Did you read my feedback? There is no "once that gets in". DTS is an
>>>>> independent hardware description and your patchset claiming there is
>>>>> dependency is just broken.
>>>>>
>>>>> I am repeating this since few emails, so shall I NAK it that you will
>>>>> address the main issue you have?
>>>>>
>>>>> Best regards,
>>>>> Krzysztof
>>>> Hi Krzysztof
>>>>
>>>> SC7180 and QCS615 use the same video core. Only difference lies in the
>>>> freq_table for the video. Freq_table is generally determined at SOC level.
>>>> The Venus driver does not currently handle freq_table compatibility well
>>>> across platforms. This patch enables the driver to use the OPP-table from
>>>> the DT, addressing the frequency compatibility issue.
>>> This does not resolve the main problem at all. If SW cannot use the
>>> fallback alone, your fallback has no meaning and is not only confusing
>>> but actually incorrect. And based on previous statements like
>>> "overclocking" it is not only incorrect, but even harmful.
>>>
>>> Best regards,
>>> Krzysztof
>> The fallback is only triggered when there is no OPP table in the DT.
> 
> No. I don't think you understand how fallback works. Fallback will be
> applied on any QCS615 DTS without front compatible.

Please read each other's messages..

Krzysztof refers to the fallback compatible mechanism, which means
the proposed QCS615 node will match against the driver containing the
sc7180 compatible.

BOD refers to the driver falling back to using the hardcoded sc7180
freq_table when the OPP table is absent (which will not be the case
for QCS615 since the node will be introduced with an OPP table on
day 0).

This patchset is okay to merge in proposed order (dt patches a cycle
after the venus patch)

Konrad