linux-kernel - Re: [PATCH 2/5] thermal: qcom: Add support for LMh driver

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Message-ID: <be5f133e-5fae-9a61-3cf5-7e611a17bc77@linaro.org>
Date:   Fri, 18 Jun 2021 17:53:11 -0400
From:   Thara Gopinath <thara.gopinath@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     agross@...nel.org, rui.zhang@...el.com, daniel.lezcano@...aro.org,
        viresh.kumar@...aro.org, rjw@...ysocki.net, robh+dt@...nel.org,
        linux-arm-msm@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 2/5] thermal: qcom: Add support for LMh driver



On 6/18/21 1:54 PM, Bjorn Andersson wrote:
> On Mon 14 Jun 20:38 CDT 2021, Thara Gopinath wrote:
>> On 6/14/21 4:53 PM, Bjorn Andersson wrote:
>>> On Tue 08 Jun 17:29 CDT 2021, Thara Gopinath wrote:
>>>> diff --git a/drivers/thermal/qcom/Makefile b/drivers/thermal/qcom/Makefile
> [..]
>>>> +static irqreturn_t lmh_handle_irq(int hw_irq, void *data)
>>>> +{
>>>> +	struct lmh_hw_data *lmh_data = data;
>>>> +	int irq = irq_find_mapping(lmh_data->domain, 0);
>>>> +
>>>> +	/*
>>>> +	 * Disable interrupt and call the cpufreq driver to handle the interrupt
>>>> +	 * cpufreq will enable the interrupt once finished processing.
>>>> +	 */
>>>> +	disable_irq_nosync(lmh_data->irq);
>>>
>>> The contract between this driver's disabling of the IRQ and the
>>> cpufreq-hw driver's enabling it when we're done polling does worry me.
>>>
>>> In the case of EPSS, don't we disable the interrupt during the polling
>>> there as well? If that's the case wouldn't it be better to implement
>>> irq_chip->irq_disable and have the cpufreq-hw driver do the disable in
>>> both cases?
>>
>> Yes. You are right. In case of EPSS, the cpufreq-hw will have to disable the
>> interrupt. I did think of the approach you suggested here. My only issue is
>> that we will dispatch the interrupt to cpufreq-hw without it disabling it
>> and hence the interrupt could fire again, right ?
>>
> 
> Does it fire again before you INTR_CLK it?

You mean clear it ? I couldn't reproduce it either way. I did not try 
the irq_chip->irq_disable either. So I will give it a try and if my 
tests pass , I will post it.

> 
> Regards,
> Bjorn
> 

-- 
Warm Regards
Thara (She/Her/Hers)