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

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Message-ID: <5b6864a9-f0ee-4bc5-aba2-c165d14b0b75@kernel.org>
Date: Sat, 7 Jun 2025 11:46:20 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: 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 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.


Best regards,
Krzysztof