linux-kernel - Re: [PATCH] thermal/drivers/qcom/lmh: Remove spurious IRQF

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Message-ID: <o5i2yrwpjxugzsyec7gkkxaclptshcn2swjwzeb2pxhqngj5y5@4ceaeiddvdyq>
Date: Sat, 31 Jan 2026 19:16:24 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Mark Brown <broonie@...nel.org>
Cc: Amit Kucheria <amitk@...nel.org>,
        Thara Gopinath <thara.gopinath@...il.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Zhang Rui <rui.zhang@...el.com>, Lukasz Luba <lukasz.luba@....com>,
        linux-arm-msm@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Aishwarya TCV <Aiswarya.TCV@....com>
Subject: Re: [PATCH] thermal/drivers/qcom/lmh: Remove spurious IRQF_ONESHOT

On Sat, Jan 31, 2026 at 03:07:04PM +0000, Mark Brown wrote:
> On Sat, Jan 31, 2026 at 08:59:03AM +0200, Dmitry Baryshkov wrote:
> > On Fri, Jan 30, 2026 at 04:54:45PM +0000, Mark Brown wrote:
> 
> > > This warning is there because IRQF_ONESHOT is only meaningful when there is
> > > a threaded interrupt handler and this driver does not register one. Just
> > > remove IRQF_ONESHOT, it wasn't doing anything.
> 
> > I think it might be not that easy. The IRQ is level-triggered, with the
> > IRQ source (if I'm not mistaken) cointinuing to be high level while CPU
> > is overheated. By removing this IRQF_ONESHOT we might get an IRQ storm.
> 
> See the commit log for aef30c8d569c ("genirq: Warn about using
> IRQF_ONESHOT without a threaded handler"), and note that a oneshot
> interrupt will be unmasked if the main handler directly handles it and
> returns IRQ_HANDLED instead of waking the thread with IRQ_WAKE_THREAD.
> The handler in this driver unconditionally returns IRQ_HANDLED.

And looking how it all works, it looks like qcom-cpufreq-hw disables the
IRQ generated by the LMH driver, which in turn disables the LMH IRQ.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>


> The above sounds like the interrupt needs to be edge triggered?

Well, it is a level IRQ, it signals that thermal mitigation is required.

-- 
With best wishes
Dmitry