Re: [PATCH] i2c: imx: use usleep_range(50,100) instead of udelay(50)

From	Wolfram Sang <wsa@the-dreams.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH] i2c: imx: use usleep_range(50,100) instead of udelay(50)
Date	2016-04-26 23:40 +0200
Message-ID	<rsiS6-6t0-21@gated-at.bofh.it> (permalink)
References	<rs4Fs-2Nr-13@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Tue, Apr 26, 2016 at 08:27:46AM +0200, Dirk Behme wrote:
> From: Oleksij Rempel <linux@rempel-privat.de>
> 
> Documentation/timers/timers-howto.txt recommends to use
> usleep_range on delays > 10usec. According to my test results
> with Neonode zForce touchscreen driver, usleep_range indeed
> reduces CPU load.
> 
> Stats collected with "./perf record -a -g -F 1000 sleep 10"
> 
> i2c-imx with udelay(50):
> 34.19% 0.00% irq/220-Neonode [kernel.kallsyms] [k] irq_thread
>     ---irq_thread
>        |--33.75%--irq_thread_fn
>        |    |--19.27%--0x7f08a878
>        |    |     i2c_master_recv
>        |    |     i2c_transfer
>        |    |     __i2c_transfer
>        |    |     i2c_imx_xfer
>        |    |     |--11.71%--i2c_imx_trx_complete

Reworded $subject to match code and applied to for-next, thanks!

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[PATCH] i2c: imx: use usleep_range(50,100) instead of udelay(50) Dirk Behme <dirk.behme@de.bosch.com> - 2016-04-26 08:30 +0200
  Re: [PATCH] i2c: imx: use usleep_range(50,100) instead of udelay(50) Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com> - 2016-04-26 13:10 +0200
    Re: [PATCH] i2c: imx: use usleep_range(50,100) instead of udelay(50) Dirk Behme <dirk.behme@de.bosch.com> - 2016-04-26 14:30 +0200
  Re: [PATCH] i2c: imx: use usleep_range(50,100) instead of udelay(50) Wolfram Sang <wsa@the-dreams.de> - 2016-04-26 23:40 +0200

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