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

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Date:   Fri, 18 Jun 2021 12:54:44 -0500
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Thara Gopinath <thara.gopinath@...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 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?

Regards,
Bjorn