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

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Date:   Mon, 6 Sep 2021 08:13:57 +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 11:03 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.


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
>