From: Wolfram Sang <wsa@the-dreams.de>
To: Gao Pan <b54642@freescale.com>
Cc: u.kleine-koenig@pengutronix.de, linux-i2c@vger.kernel.org,
B20596@freescale.com, b38611@freescale.com,
kernel@pengutronix.de, Heiner Kallweit <hkallweit1@gmail.com>
Subject: Re: [Patch V10] i2c: imx: add runtime pm support to improve the performance
Date: Sun, 3 Jan 2016 19:10:10 +0100 [thread overview]
Message-ID: <20160103181009.GA1522@katana> (raw)
In-Reply-To: <1449800649-32763-1-git-send-email-b54642@freescale.com>
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On Fri, Dec 11, 2015 at 10:24:09AM +0800, Gao Pan wrote:
> In our former i2c driver, i2c clk is enabled and disabled in
> xfer function, which contributes to power saving. However,
> the clk enable process brings a busy wait delay until the core
> is stable. As a result, the performance is sacrificed.
>
> To weigh the power consumption and i2c bus performance, runtime
> pm is the good solution for it. The clk is enabled when a i2c
> transfer starts, and disabled after a specifically defined delay.
>
> If CONFIG_PM is disabled the net result of this patch is that the
> clock is never disabled.
>
> Without the patch the test case (many eeprom reads) executes with approx:
> real 1m7.735s
> user 0m0.488s
> sys 0m20.040s
>
> With the patch the same test case (many eeprom reads) executes with approx:
> real 0m54.241s
> user 0m0.440s
> sys 0m5.920s
>
> Signed-off-by: Fugang Duan <B38611@freescale.com>
> Signed-off-by: Gao Pan <b54642@freescale.com>
> Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Applied to for-next, thanks! Also much thanks to Uwe and Heiner for the
reviews of all these versions!
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prev parent reply other threads:[~2016-01-03 18:10 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-11 2:24 [Patch V10] i2c: imx: add runtime pm support to improve the performance Gao Pan
2016-01-03 18:10 ` Wolfram Sang [this message]
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