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

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Message-ID: <e3637f0f-1e72-db3a-f744-ade0e878cfc5@linaro.org>
Date:   Mon, 11 Feb 2019 12:23:20 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Stuart Menefy <stuart.menefy@...hembedded.com>,
        linux-samsung-soc@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...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 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?


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