Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH 0/2] Subject: [PATCH 0/2] clocksource: exynos_mct: Clear
 timer interrupt when shutting down
To:     Stuart Menefy <stuart.menefy@mathembedded.com>,
        linux-samsung-soc@vger.kernel.org,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Kukjin Kim <kgene@kernel.org>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
From:   Marek Szyprowski <m.szyprowski@samsung.com>
Message-ID: <e22c175a-d88a-81a7-9faa-42bb4fe09a22@samsung.com>
Date:   Mon, 11 Feb 2019 08:14:01 +0100
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101
        Thunderbird/60.5.0
MIME-Version: 1.0
In-Reply-To: <20190210225114.20110-1-stuart.menefy@mathembedded.com>
Content-Transfer-Encoding: 7bit
Content-Language: en-US
Content-Type: text/plain; charset="utf-8"
CMS-TYPE: 201P
References: <CGME20190210225147epcas3p4cedebfc5692274bc6135ceabbcf2642d@epcas3p4.samsung.com>
        <20190210225114.20110-1-stuart.menefy@mathembedded.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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@samsung.com>

> Stuart Menefy (2):
>   clocksource: exynos_mct: Move one-shot check from tick clear to ISR
>   clocksource: exynos_mct: Clear timer interrupt when shutdown
>
>  drivers/clocksource/exynos_mct.c | 23 ++++++++++++-----------
>  1 file changed, 12 insertions(+), 11 deletions(-)
>
Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland