linux-kernel - Re: [PATCH 3/3] media: iris: Add support for SM8750 (VPU v3.5)

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Message-ID: <cd51f5ee-8f2c-486f-9ab1-526088b17127@linaro.org>
Date: Thu, 17 Jul 2025 14:34:27 +0200
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Dikshita Agarwal <quic_dikshita@...cinc.com>,
 Vikash Garodia <quic_vgarodia@...cinc.com>,
 Abhinav Kumar <abhinav.kumar@...ux.dev>,
 Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
 Mauro Carvalho Chehab <mchehab@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Philipp Zabel <p.zabel@...gutronix.de>
Cc: linux-media@...r.kernel.org, linux-arm-msm@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] media: iris: Add support for SM8750 (VPU v3.5)

On 17/07/2025 14:22, Dikshita Agarwal wrote:
> 
> 
> On 7/17/2025 4:24 PM, Krzysztof Kozlowski wrote:
>> On 17/07/2025 12:50, Dikshita Agarwal wrote:
>>>>>>>> +	for (i = 0; i < core->iris_platform_data->num_vpp_pipe; i++) {
>>>>>>>> +		ret = readl_poll_timeout(core->reg_base + VCODEC_SS_IDLE_STATUSN + 4 * i,
>>>>>>>> +					 val, val & 0x400000, 2000, 20000);
>>>>>>>> +		if (ret)
>>>>>>>> +			goto disable_power;
>>>>>>>> +	}
>>>>>>>> +
>>>>>>>> +	ret = readl_poll_timeout(core->reg_base + AON_WRAPPER_MVP_NOC_LPI_STATUS,
>>>>>>>> +				 val, val & BIT(0), 200, 2000);
>>>>>>> what are you polling here for?
>>>>>>
>>>>>>
>>>>>> This is not different than existing code. I don't understand why you are
>>>>>> commenting on something which is already there.
>>>>>
>>>>> Which code are you referring to?
>>>>
>>>> To the existing vpu33 which had Reviewed-by: Vikash Garodia
>>>> <quic_vgarodia@...cinc.com>
>>>>
>>>> You understand that everything here is the same, everything is a copy
>>>> while adding just few more things?
>>>>
>>>> My patch is not doing in this respect anything different that what you
>>>> reviewed.
>>>>
>>>
>>> It seems to have been missed in vpu33 power off sequence as well and should
>>> be fixed.
>>>
>>> Still, as mentioned earlier as well, your reference should be
>>> HPG/downstream driver of SM8750 not the previous generation (SM8650).
>>
>> Yes and partially no, because we write upstream code matching or
>> extending existing upstream driver. As you said earlier, downstream is
>> not the truth always:
> 
> You're writing the power sequence for a new generation, so referencing the
> previous generation is totally wrong. Power sequences can vary between


No. I am extending existing source code in hopefully compatible or
matching style.

We do not follow here downstream approaches of reimplementing everything
from scratch on every new generation.

> generations — that's precisely why HPG exists.
> 
> I've already pointed this out multiple times, but let me reiterate one last
> time:
> The current power sequence code is incomplete.
> Copying the SM8650 code to SM8750 is not appropriate — it's the wrong
> reference.
You only pointed out missing AON_WRAPPER_MVP_NOC_LPI_CONTROL, so
"multiple times" is not accurate.


Best regards,
Krzysztof