linux-kernel - Re: [PATCH v2 3/3] media: iris: Add support for SM8750 (VPU v3.5)

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Message-ID: <5b34ebed-b993-4f0d-bb30-0dfab1cff95d@linaro.org>
Date: Thu, 28 Aug 2025 15:18:15 +0200
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Krzysztof Kozlowski <krzk@...nel.org>,
 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 v2 3/3] media: iris: Add support for SM8750 (VPU v3.5)

On 12/08/2025 10:16, Krzysztof Kozlowski wrote:
>>> +	ret = readl_poll_timeout(core->reg_base + WRAPPER_IRIS_CPU_NOC_LPI_STATUS,
>>> +				 val, val & BIT(0), 200, 2000);
>>> +	if (ret)
>>> +		goto disable_power;
>>> +
>>> +	writel(0x0, core->reg_base + WRAPPER_IRIS_CPU_NOC_LPI_CONTROL);
>>> +
>>> +	writel(REQ_POWER_DOWN_PREP, core->reg_base + AON_WRAPPER_MVP_VIDEO_CTL_NOC_LPI_CONTROL);
>>
>>
>> Read initial status of AON_WRAPPER_MVP_VIDEO_CTL_NOC_LPI_STATUS
>>
>> based on value, run the retry loop.
>> This loop runs till the desired LPI state is reached i.e. BIT(0) is set,
>> and hardware is idle i.e. BIT(1) or BIT(2) are unset. This suggests a
>> situation where the hardware might be stuck or slow to transition.
>>
>> This sequence was not needed for SM8650 since it doesn't have
>> AON_WRAPPER_MVP_VIDEO_CTL_NOC_LPI_CONTROL/STATUS registers.
>> But required for SM8750, so please add.
> 
> 
> Sure

I am implementing the changes you asked and this one I will skip,
because the loop is already there:

> 
>>
>>
>>> +	ret = readl_poll_timeout(core->reg_base + AON_WRAPPER_MVP_VIDEO_CTL_NOC_LPI_STATUS,
>>> +				 val, val & (BIT(0) | BIT(1) | BIT(2)), 15, 1000);



Best regards,
Krzysztof