linux-kernel - Re: [PATCH] spi: tegra20-slink: Fix runtime PM imbalance on error

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Message-ID: <046fe754-96d7-4530-2b70-e1991470ac0f@nvidia.com>
Date:   Thu, 21 May 2020 09:46:48 +0100
From:   Jon Hunter <jonathanh@...dia.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Dinghao Liu <dinghao.liu@....edu.cn>
CC:     Kangjie Lu <kjlu@....edu>, Laxman Dewangan <ldewangan@...dia.com>,
        "Mark Brown" <broonie@...nel.org>,
        Thierry Reding <thierry.reding@...il.com>,
        linux-spi <linux-spi@...r.kernel.org>,
        <linux-tegra@...r.kernel.org>,
        "Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] spi: tegra20-slink: Fix runtime PM imbalance on error


On 21/05/2020 09:38, Jon Hunter wrote:
> 
> On 21/05/2020 09:04, Andy Shevchenko wrote:
>> On Thu, May 21, 2020 at 10:50 AM Dinghao Liu <dinghao.liu@....edu.cn> wrote:
>>>
>>> pm_runtime_get_sync() increments the runtime PM usage counter even
>>> when it returns an error code. Thus a pairing decrement is needed on
>>> the error handling path to keep the counter balanced.
>>
>> ...
>>
>>>         ret = pm_runtime_get_sync(&pdev->dev);
>>>         if (ret < 0) {
>>>                 dev_err(&pdev->dev, "pm runtime get failed, e = %d\n", ret);
>>
>>> +               pm_runtime_put(&pdev->dev);
>>
>> For all your patches, please, double check what you are proposing.
>>
>> Here, I believe, the correct one will be _put_noidle().
>>
>> AFAIU you are not supposed to actually suspend the device in case of error.
>> But I might be mistaken, thus see above.
>>
>>>                 goto exit_pm_disable;
>>>         }
> 
> 
> Is there any reason why this is not handled in pm_runtime_get itself?

Ah I see a response from Rafael here:
https://lkml.org/lkml/2020/5/20/1100

OK so this is intentional and needs to be fixed.

Jon

-- 
nvpublic