linux-kernel - Re: [PATCH v5 01/36] i2c: tegra: Make tegra_i2c_flush

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Message-ID: <272065fe-950a-24e9-ba8f-8b1a782c203f@gmail.com>
Date:   Mon, 7 Sep 2020 17:31:37 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Wolfram Sang <wsa@...-dreams.de>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        linux-tegra@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 01/36] i2c: tegra: Make tegra_i2c_flush_fifos() usable
 in atomic transfer

07.09.2020 10:56, Andy Shevchenko пишет:
> On Sun, Sep 6, 2020 at 9:51 PM Dmitry Osipenko <digetx@...il.com> wrote:
>>
>> The tegra_i2c_flush_fifos() shouldn't sleep in atomic transfer and jiffies
>> are not updating if interrupts are disabled. Let's switch to use iopoll
>> API helpers for register-polling. The iopoll API provides helpers for both
>> atomic and non-atomic cases.
>>
>> Note that this patch doesn't fix any known problem because normally FIFO
>> is flushed at the time of starting a new transfer.
> 
> ...
> 
>> +       if (i2c_dev->is_curr_atomic_xfer)
>> +               err = readl_relaxed_poll_timeout_atomic(addr, val, !(val & mask),
>> +                                                       1000, 1000000);
>> +       else
>> +               err = readl_relaxed_poll_timeout(addr, val, !(val & mask),
>> +                                                1000, 1000000);
>> +
>> +       if (err) {
>> +               dev_err(i2c_dev->dev, "failed to flush FIFO\n");
> 
>> +               return err;
>>         }
>>         return 0;
> 
> return err; ?
> 

The return 0 is intentional here because returned "err" implies that
error happened and error code is returned, while 0 explicitly shows the
success status. Hence it's always cleaner and more expressive to
directly return 0 on success, IMO. I'd prefer to keep this part as-is.