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Subject: Re: [PATCH v2 1/2] i2c: tegra: Better handle case where CPU0 is busy
 for a long time
To:     Jon Hunter <jonathanh@nvidia.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        Laxman Dewangan <ldewangan@nvidia.com>,
        Wolfram Sang <wsa@the-dreams.de>,
        Manikanta Maddireddy <mmaddireddy@nvidia.com>,
        Vidya Sagar <vidyas@nvidia.com>
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        linux-kernel@vger.kernel.org
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From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <77a31b2f-f525-ba9e-f1ae-2b474465bde4@gmail.com>
Date:   Wed, 22 Apr 2020 16:40:14 +0300
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21.04.2020 22:42, Jon Hunter пишет:
> 
> On 21/04/2020 16:08, Dmitry Osipenko wrote:
>> 21.04.2020 17:40, Jon Hunter пишет:
>>>
>>> On 21/04/2020 14:25, Dmitry Osipenko wrote:
>>>> 21.04.2020 12:49, Jon Hunter пишет:
>>>> ...
>>>>> I can try the above, but I agree it would be best to avoid messing with
>>>>> the suspend levels if possible.
>>>>
>>>> Will be awesome if you could try it and report back the result.
>>>>
>>>
>>> I gave it a try but suspend still fails.
>>
>> Perhaps the RPM's -EACCES is returned from here:
>>
>> https://elixir.free-electrons.com/linux/v5.7-rc2/source/drivers/base/power/runtime.c#L723
>>
>> Which suggests that I2C is accessed after being suspended. I guess the
>> PCIe driver suspends after the I2C and somehow my change affected the
>> suspension order, although not sure how.
>>
>> Jon, could you please try to enable PM logging and post the log? Please
>> also post log of the working kernel version, so that we could compare
>> the PM sequence.
>>
>> Something like this should enable the logging: "echo 1 >
>> /sys/power/pm_trace" + there is RPM tracing.
> 
> Unfortunately, after enabling that I don't any output and so no help there.

1. I now tried to check the pm_trace myself and found that it's
available only on X86, my bad.

2. Jon, could you please clarify what exactly you were trying to test?

3. Is it only the Cardhu board that is affected by this problem?

4. Could you please try to add this to the kernel's cmdline and post the
logs:

tp_printk
trace_event=rpm_suspend,rpm_resume,rpm_usage,rpm_idle,rpm_return_int