linux-kernel - Re: [PATCH v2] thermal: imx: implement runtime PM support

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Message-ID: <8692108c-1b46-3d3d-6911-300ac27c2980@ysoft.com>
Date:   Wed, 10 Nov 2021 11:07:31 +0100
From:   Michal Vokáč <michal.vokac@...ft.com>
To:     Oleksij Rempel <o.rempel@...gutronix.de>
Cc:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        linux-pm@...r.kernel.org, Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Amit Kucheria <amitk@...nel.org>, linux-kernel@...r.kernel.org,
        Andrzej Pietrasiewicz <andrzej.p@...labora.com>,
        NXP Linux Team <linux-imx@....com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        David Jander <david@...tonic.nl>,
        Zhang Rui <rui.zhang@...el.com>,
        Fabio Estevam <festevam@...il.com>,
        linux-arm-kernel@...ts.infradead.org,
        Petr Benes <petrben@...il.com>
Subject: Re: [PATCH v2] thermal: imx: implement runtime PM support

On 25. 10. 21 13:06, Petr Benes wrote:
> Hi Oleksij,
> 
> On Thu, 21 Oct 2021 at 19:21, Oleksij Rempel <o.rempel@...gutronix.de> wrote:
>>
>> Hi Petr,
>>
>> On Wed, Oct 20, 2021 at 05:53:03PM +0200, Petr Benes wrote:
>>> On Wed, 20 Oct 2021 at 07:05, Oleksij Rempel <o.rempel@...gutronix.de> wrote:
>>>>
>>>> Hi Petr and Michal,
>>>>
>>>> I forgot to add you for v2 in CC. Please test/review this version.
>>>
>>> Hi Oleksij,
>>>
>>> It works good. with PM as well as without PM. The only minor issue I found is,
>>> that the first temperature reading (when the driver probes) fails. That is
>>> (val & soc_data->temp_valid_mask) == 0) holds true. How does
>>> pm_runtime_resume_and_get() behave in imx_thermal_probe()?
>>> Does it go through imx_thermal_runtime_resume() with usleep_range()?
>>
>> How exactly did you reproduce it? Even more or less understanding how
> 
> I just placed my debug print into get_temp()
> 
>      if ((val & soc_data->temp_valid_mask) == 0) {
>          dev_dbg(&tz->device, "temp measurement never finished\n");
>          printk("Wrong temperature reading!!!!!!\n");
>          return -EAGAIN;
>      }
> 
>> this can potentially happen, i never had this issue on my HW. Is it something
>> HW specific?
> 
> IMHO it is just product of the following sequence:
> 
> pm_runtime_set_active(&pdev->dev);
> pm_runtime_enable(data->dev);
> pm_runtime_resume_and_get(data->dev);
> thermal_zone_device_enable(data->tz);
> 
> With assumption imx_thermal_runtime_resume() didn't run,
> hence the sensor didn't get enough time to come up.
> 
> I didn't have time to spend it on and you have better knowledge of the
> area. If it is not that straightforward I can try to diagnose it better.
>
Hi Oleksij,
Did you manage to further debug and reproduce this problem?
Do you plan to send the v3?

Regarding your question about the HW - this problem occured once we
upgraded the SoC on our SBC from i.MX6DL to i.MX6Q/QP. With the DualLite
we never had this problem but the Quad is getting hot quite fast.
We have pretty limited cooling options so the core is operated at its
upper temperature limits when fully loaded.

Best regards,
Michal