linux-kernel - Re: [PATCH v3 01/22] i2c: tegra: Make tegra_i2c_flush

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Message-ID: <957928b1-0b74-f263-b699-5a83db77df62@gmail.com>
Date:   Thu, 3 Sep 2020 16:49:02 +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 v3 01/22] i2c: tegra: Make tegra_i2c_flush_fifos() usable
 in atomic transfer

03.09.2020 14:02, Andy Shevchenko пишет:
> On Thu, Sep 3, 2020 at 3:53 AM 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. Hence let's use proper delay
>> functions and use ktime API in order not to hang atomic transfer. Note
>> that this patch doesn't fix any known problem because normally FIFO is
>> flushed at the time of starting a new transfer.
> 
>> +       /*
>> +        * ktime_get() may take up to couple milliseconds in a worst case
>> +        * and normally FIFOs are flushed, hence let's check the state before
>> +        * proceeding to polling.
>> +        */
> 
> Everything, including above can be done by using macros from iopoll.h. Why not?

Perhaps indeed it should be possible to use the common macros, at least
I can't recall why I chose not to use them. Maybe because it appeared to
me that the current variant is a bit nicer than:

if (atomic)
	read_poll_atomic()
else
	read_poll()


I'll consider to use the common iopoll macros in v4, thanks!