linux-kernel - Re: [PATCH v8 00/29] Rework the trip points creation

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Date:   Wed, 5 Oct 2022 14:37:14 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Marek Szyprowski <m.szyprowski@...sung.com>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        rui.zhang@...el.com,
        Broadcom Kernel Team <bcm-kernel-feedback-list@...adcom.com>,
        Support Opensource <support.opensource@...semi.com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        NXP Linux Team <linux-imx@....com>,
        Andy Gross <agross@...nel.org>,
        Bartlomiej Zolnierkiewicz <bzolnier@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Alim Akhtar <alim.akhtar@...sung.com>, netdev@...r.kernel.org,
        platform-driver-x86@...r.kernel.org,
        linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-samsung-soc@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-omap@...r.kernel.org, rafael@...nel.org
Subject: Re: [PATCH v8 00/29] Rework the trip points creation


Hi Marek,

On 03/10/2022 23:18, Daniel Lezcano wrote:

[ ... ]

>> I've tested this v8 patchset after fixing the issue with Exynos TMU with
>> https://lore.kernel.org/all/20221003132943.1383065-1-daniel.lezcano@linaro.org/ 
>>
>> patch and I got the following lockdep warning on all Exynos-based boards:
>>
>>
>> ======================================================
>> WARNING: possible circular locking dependency detected
>> 6.0.0-rc1-00083-ge5c9d117223e #12945 Not tainted
>> ------------------------------------------------------
>> swapper/0/1 is trying to acquire lock:
>> c1ce66b0 (&data->lock#2){+.+.}-{3:3}, at: exynos_get_temp+0x3c/0xc8
>>
>> but task is already holding lock:
>> c2979b94 (&tz->lock){+.+.}-{3:3}, at:
>> thermal_zone_device_update.part.0+0x3c/0x528
>>
>> which lock already depends on the new lock.
> 
> I'm wondering if the problem is not already there and related to 
> data->lock ...
> 
> Doesn't the thermal zone lock already prevent racy access to the data 
> structure?
> 
> Another question: if the sensor clock is disabled after reading it, how 
> does the hardware update the temperature and detect the programed 
> threshold is crossed?

just a gentle ping, as the fix will depend on your answer ;)

Thanks

   -- D.

[ ... ]


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