linux-kernel - Re: [PATCH 0/2] Subject: [PATCH 0/2] clocksource: exynos_mct: Clear timer interrupt when shutting down

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Date:   Mon, 11 Feb 2019 12:34:58 +0100
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Stuart Menefy <stuart.menefy@...hembedded.com>,
        "linux-samsung-soc@...r.kernel.org" 
        <linux-samsung-soc@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kukjin Kim <kgene@...nel.org>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 0/2] Subject: [PATCH 0/2] clocksource: exynos_mct: Clear
 timer interrupt when shutting down

On Mon, 11 Feb 2019 at 12:23, Daniel Lezcano <daniel.lezcano@...aro.org> wrote:
>
> On 11/02/2019 08:14, Marek Szyprowski wrote:
> > Hi Stuart
> >
> > On 2019-02-10 23:51, Stuart Menefy wrote:
> >> When debugging suspend problems on Exynos 5260, I had a large number
> >> of debugging prints going to the serial port after interrupts
> >> had been disabled but before the timer interrupt was shutdown. This
> >> was long enough for a timer tick to occur, but as interrupts were
> >> disabled the ISR didn't run, and so the interrupt wasn't cleared.
> >> Later when the timer was shutdown the interrupt was left asserted and
> >> so the wfi at the heart of the suspend code didn't wait, causing
> >> the suspend to fail.
> >>
> >> Currently the code which stops the timer when it is on one-shot mode
> >> and the interrupt occurs is in exynos4_mct_tick_clear(), meaning if we
> >> called this from the shutdown code exynos4_mct_tick_stop() could be
> >> called twice. So first restructure the existing code, so the check for
> >> one-shot mode and stopping the timer is moved to the ISR, leaving
> >> exynos4_mct_tick_clear() just clearing the interrupt flag.
> >>
> >> Once this has been done simply call exynos4_mct_tick_clear() from
> >> set_state_shutdown().
> >
> > This also fixes mysterious suspend failures on Odroid XU3/XU4/HC1 :)
> >
> > Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>
>
> Applied. Shall I add the stable@ tag?

Makes sense - for the second patch, although first is a prerequisite.
It should be backported up to v4.3 (the code differ a lot on older
versions).

Best regards,
Krzysztof