Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v2 1/2] i2c: tegra: Better handle case where CPU0 is busy
 for a long time
From:   Dmitry Osipenko <digetx@gmail.com>
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>
Cc:     linux-i2c@vger.kernel.org, linux-tegra@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20200324191217.1829-1-digetx@gmail.com>
 <20200324191217.1829-2-digetx@gmail.com>
 <1e259e22-c300-663a-e537-18d854e0f478@nvidia.com>
 <f59ba318-8e99-c486-fa4d-1ee28a7b203d@gmail.com>
 <b01cec76-bb39-9fb5-8f6e-4023c075e6b3@gmail.com>
 <8cd085e1-f9fd-6ec0-9f7a-d5463f176a63@nvidia.com>
 <db1132ce-53a8-371c-98e0-cb7cd91d5c7d@gmail.com>
 <fa344989-4cce-0d2c-dc93-4ca546823160@nvidia.com>
 <bba0a93a-8ec4-eda6-97f3-fb2ab0b9b503@gmail.com>
 <6f07e5c8-7916-7ea2-2fe7-d05f8f011471@nvidia.com>
 <77a31b2f-f525-ba9e-f1ae-2b474465bde4@gmail.com>
 <470b4de4-e98a-1bdc-049e-6259ad603507@nvidia.com>
 <d2531fc1-b452-717d-af71-19497e14ef00@gmail.com>
 <a5198024-7273-74c4-b4f4-3a29d042bc36@nvidia.com>
 <da5985f4-44b3-336d-207d-4c0388806f95@gmail.com>
Message-ID: <5fc71168-e4ac-11f6-dbf1-e80f4fae8d1a@gmail.com>
Date:   Mon, 27 Apr 2020 17:13:56 +0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.7.0
MIME-Version: 1.0
In-Reply-To: <da5985f4-44b3-336d-207d-4c0388806f95@gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

27.04.2020 15:46, Dmitry Osipenko пишет:
> 23.04.2020 13:56, Jon Hunter пишет:
>>>> So I think that part of the problem already existed prior to these
>>>> patches. Without your patches I see ...
>>>>
>>>> [   59.543528] tegra-i2c 7000d000.i2c: i2c transfer timed out
>>>> [   59.549036] vdd_sata,avdd_plle: failed to disable
>>>> [   59.553778] Failed to disable avdd-plle: -110
>>>> [   59.558150] tegra-pcie 3000.pcie: failed to disable regulators: -110
>>> Does this I2C timeout happen with my patches? Could you please post full
>>> logs of an older and the recent kernel versions?
>> I believe that it does, but I need to check.
>>
> 
> Jon, could you please confirm that you're seeing those regulator-disable
> errors with my patch? I don't see those errors in yours original log [1].
> 
> [1]
> https://lore.kernel.org/lkml/1e259e22-c300-663a-e537-18d854e0f478@nvidia.com/
> 
> Again, could you please post the *full* logs?
> 
> If regulator's disabling was "failing" before without my patch because
> of the I2C interrupt being force-disabled during of NOIRQ phase, and now
> regulator's disabling succeeds with my patch because IRQ is manually
> handled after the timeout, then this could be bad. It means that
> regulator was actually getting disabled, but I2C driver was timing out
> because interrupt couldn't be handled in NOIRQ phase, which should
> result in a dead PCIe on a resume from suspend since regulator's core
> thinks that regulator is enabled (I2C said it failed to disable), while
> it is actually disabled.
> 
> Do you have anything plugged into the PCIe slot in yours testing farm?
> It wouldn't surprise me if the plugged card isn't functional after
> resume from suspend on a stable kernels.
> 

I actually now see that interrupt is not allowed to be enabled during
the NOIRQ phase:

https://elixir.bootlin.com/linux/v5.7-rc3/source/kernel/irq/manage.c#L640

it should be worthwhile to turn it into a WARN_ON.