linux-kernel - Re: [PATCH 08/25] media: atmel: properly get pm

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Message-ID: <8c7d26ce-e646-aaf7-15ab-6f047425161e@microchip.com>
Date:   Mon, 13 Sep 2021 10:26:43 +0000
From:   <Eugen.Hristev@...rochip.com>
To:     <mchehab+huawei@...nel.org>
CC:     <Jonathan.Cameron@...wei.com>, <linuxarm@...wei.com>,
        <mauro.chehab@...wei.com>, <alexandre.belloni@...tlin.com>,
        <Ludovic.Desroches@...rochip.com>, <mchehab@...nel.org>,
        <Nicolas.Ferre@...rochip.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-media@...r.kernel.org>,
        <Claudiu.Beznea@...rochip.com>
Subject: Re: [PATCH 08/25] media: atmel: properly get pm_runtime

On 9/6/21 11:13 AM, Eugen Hristev - M18282 wrote:
> On 9/6/21 11:03 AM, Mauro Carvalho Chehab wrote:
>> Hi Eugen,
>>
>> Em Thu, 10 Jun 2021 12:00:42 +0000
>> <Eugen.Hristev@...rochip.com> escreveu:
>>
>>> On 6/10/21 12:38 PM, Mauro Carvalho Chehab wrote:
>>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>>>
>>>> Em Thu, 10 Jun 2021 09:04:07 +0000
>>>> <Eugen.Hristev@...rochip.com> escreveu:
>>>>
>>>>>>> diff --git a/drivers/media/platform/atmel/atmel-isc-base.c b/drivers/media/platform/atmel/atmel-isc-base.c
>>>>>>> index fe3ec8d0eaee..ce8e1351fa53 100644
>>>>>>> --- a/drivers/media/platform/atmel/atmel-isc-base.c
>>>>>>> +++ b/drivers/media/platform/atmel/atmel-isc-base.c
>>>>>>> @@ -294,9 +294,13 @@ static int isc_wait_clk_stable(struct clk_hw *hw)
>>>>>>>      static int isc_clk_prepare(struct clk_hw *hw)
>>>>>>>      {
>>>>>>>           struct isc_clk *isc_clk = to_isc_clk(hw);
>>>>>>> +     int ret;
>>>>>>>
>>>>>>> -     if (isc_clk->id == ISC_ISPCK)
>>>>>>> -             pm_runtime_get_sync(isc_clk->dev);
>>>>>>> +     if (isc_clk->id == ISC_ISPCK) {
>>>>>>> +             ret = pm_runtime_resume_and_get(isc_clk->dev);
>>>>>>> +             if (ret < 0)
>>>>>>> +                     return ret;
>>>>>>> +     }
>>>>>
>>>>> Hi Mauro,
>>>>>
>>>>> With this patch, the ISC is broken on latest media tree. It looks like
>>>>> pm_runtime_resume_and_get for the ISC_ISPCK clock returns -ENOACCESS and
>>>>> thus, the probe of the driver fails:
>>>>>
>>>>> atmel-sama5d2-isc f0008000.isc: failed to enable ispck: -13
>>>>> atmel-sama5d2-isc: probe of f0008000.isc failed with error -13
>>
>> What's the current status of this issue?
> 
> Hi Mauro,
> 
> Currently, as far as I know, the ISC is broken in 5.14 and current Linux
> master. I plan to investigate this issue this week (or the next...),
> together with some other things. I want to tryout the PM part of the
> driver to see where is the problem.
> When I come up with a fix or patch, I will send it on the mailing list.
> If you have any ideas that I can try meanwhile, feel free to contact me
> to send a patch that I can test.
> 
> 

Hi Mauro,

Regarding this issue, I sent a patch on the ML that should solve it.

https://patchwork.linuxtv.org/project/linux-media/patch/20210913102254.108638-1-eugen.hristev@microchip.com/

Eugen

> Eugen
> 
> 
>>
>> If the bug still happens, we need a fix for it.
>>
>> We might revert this patch, but this would just be masking some other
>> hidden bug.
>>
>> Regards,
>> Mauro
>>
>>
>>
>>>>>
>>>>>
>>>>> Could you point out how I could fix this ? Maybe the isc_clk->dev is not
>>>>> properly handled/initialized in some other part of the code ?
>>>>
>>>> Looking at RPM implementation:
>>>>
>>>>            static int rpm_resume(struct device *dev, int rpmflags)
>>>>            {
>>>> ...
>>>>            if (dev->power.runtime_error)
>>>>                    retval = -EINVAL;
>>>>            else if (dev->power.disable_depth == 1 && dev->power.is_suspended
>>>>                && dev->power.runtime_status == RPM_ACTIVE)
>>>>                    retval = 1;
>>>>            else if (dev->power.disable_depth > 0)
>>>>                    retval = -EACCES;
>>>> ...
>>>>
>>>> It sounds that RPM is disabled for this clock. Did you call
>>>> pm_runtime_enable() before calling isc_clk_prepare()?
>>>>
>>>> Thanks,
>>>> Mauro
>>>>
>>>
>>> I tried to call pm_runtime_enable for the clk at clk_init time, but
>>> doing that makes the runtime for the ISC fail like this:
>>>
>>> atmel-sama5d2-isc f0008000.isc: Unbalanced pm_runtime_enable!
>>
>>
>>
>> Thanks,
>> Mauro
>>
>