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From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Daniel Lezcano <daniel.lezcano@oss.qualcomm.com>
Cc: Mayur Kumar <kmayur809@gmail.com>,
	 rafael@kernel.org, daniel.lezcano@kernel.org,
	 rui.zhang@intel.com,  lukasz.luba@arm.com,
	linux-pm@vger.kernel.org,  linux-kernel@vger.kernel.org
Subject: Re: [PATCH] thermal: armada: replace msleep with usleep_range for short durations
Date: Tue, 19 May 2026 09:43:45 +0200	[thread overview]
Message-ID: <87se7nsv2m.fsf@bootlin.com> (raw)
In-Reply-To: <9ae2a769-4b2a-4990-90d4-0a1c0f05ba82@oss.qualcomm.com> (Daniel Lezcano's message of "Mon, 18 May 2026 19:57:46 +0200")

Hello Mayur, Daniel,

Actually I have a couple of comments :-)

On 18/05/2026 at 19:57:46 +02, Daniel Lezcano <daniel.lezcano@oss.qualcomm.com> wrote:

> On 5/11/26 17:37, Mayur Kumar wrote:
>> The checkpatch tool warns that msleep(10) can sleep for up to 20ms.

This is a tool that gives you raw advices. Is sleeping 20ms a problem in
an init function, clearly outside of any hotpath? Honestly that does not
look like a big issue to me.

>> According to Documentation/timers/timers-howto.rst, usleep_range()

This file has been dropped in favour of a more up-to-date
Documentation/timers/delay_sleep_functions.rst in:

1f455f601e20 ("timers/Documentation: Cleanup delay/sleep documentation")

>> should be used for delays between 1ms and 20ms to provide better
>> timing accuracy.

Again, I don't see the point here, we do not need accuracy, do we?

>> Replace the 10ms msleep with a 10ms-11ms usleep_range.

10 to 11ms feels very arbitrary and has been selected just for getting
the tool happy. The above file states:
#. Use `fsleep()` whenever unsure (as it combines all the advantages of the
   others)
#. Use `*sleep()` whenever possible
#. Use `usleep_range*()` whenever accuracy of `*sleep()` is not sufficient
#. Use `*delay()` for very, very short delays

Accuracy not being a concern here, fsleep() could be the way to go, and
the actual implementation would end up being usleep_range(10000, 20000),
which is exactly what the tool complains about.

In general I would be in favour of avoiding this kind of change that is
not motivated by hardware concerns, but if you really want to fix this
checkpatch.pl warning I believe in such case you should go for an
fsleep().

Thanks,
Miquèl

      reply	other threads:[~2026-05-19  7:43 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-11 15:37 [PATCH] thermal: armada: replace msleep with usleep_range for short durations Mayur Kumar
2026-05-18 17:57 ` Daniel Lezcano
2026-05-19  7:43   ` Miquel Raynal [this message]

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