linux-kernel - Re: [PATCH] cpufreq: qcom-hw: Don't do lmh things without a throttle interrupt

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Date:   Fri, 17 Jun 2022 03:21:38 +0300
From:   Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>
To:     Stephen Boyd <swboyd@...omium.org>,
        Viresh Kumar <viresh.kumar@...aro.org>
Cc:     linux-kernel@...r.kernel.org, patches@...ts.linux.dev,
        linux-pm@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Rob Clark <robdclark@...omium.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Subject: Re: [PATCH] cpufreq: qcom-hw: Don't do lmh things without a throttle
 interrupt

On 6/17/22 01:45, Stephen Boyd wrote:
> Offlining cpu6 and cpu7 and then onlining cpu6 hangs on
> sc7180-trogdor-lazor because the throttle interrupt doesn't exist.
> Similarly, things go sideways when suspend/resume runs. That's because
> the qcom_cpufreq_hw_cpu_online() and qcom_cpufreq_hw_lmh_exit()
> functions are calling genirq APIs with an interrupt value of '-6', i.e.
> -ENXIO, and that isn't good.
> 
> Check the value of the throttle interrupt like we already do in other
> functions in this file and bail out early from lmh code to fix the hang.
> 
> Reported-by: Rob Clark <robdclark@...omium.org>
> Cc: Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>
> Cc: Bjorn Andersson <bjorn.andersson@...aro.org>
> Cc: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> Fixes: a1eb080a0447 ("cpufreq: qcom-hw: provide online/offline operations")
> Signed-off-by: Stephen Boyd <swboyd@...omium.org>
> ---
>   drivers/cpufreq/qcom-cpufreq-hw.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
> index 0253731d6d25..36c79580fba2 100644
> --- a/drivers/cpufreq/qcom-cpufreq-hw.c
> +++ b/drivers/cpufreq/qcom-cpufreq-hw.c
> @@ -442,6 +442,9 @@ static int qcom_cpufreq_hw_cpu_online(struct cpufreq_policy *policy)
>   	struct platform_device *pdev = cpufreq_get_driver_data();
>   	int ret;
>   
> +	if (data->throttle_irq <= 0)
> +		return 0;
> +
>   	ret = irq_set_affinity_hint(data->throttle_irq, policy->cpus);
>   	if (ret)
>   		dev_err(&pdev->dev, "Failed to set CPU affinity of %s[%d]\n",
> @@ -469,6 +472,9 @@ static int qcom_cpufreq_hw_cpu_offline(struct cpufreq_policy *policy)
>   
>   static void qcom_cpufreq_hw_lmh_exit(struct qcom_cpufreq_data *data)
>   {
> +	if (data->throttle_irq <= 0)
> +		return;
> +
>   	free_irq(data->throttle_irq, data);
>   }
>   
> 
Reviewed-by: Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>

--
Best wishes,
Vladimir