From: Wolfram Sang <wsa@the-dreams.de>
To: Gao Pan <b54642@freescale.com>
Cc: linux-i2c@vger.kernel.org, B20596@freescale.com,
b38611@freescale.com, u.kleine-koenig@pengutronix.de,
kernel@pengutronix.de, hkallweit1@gmail.com,
s.hauer@pengutronix.de
Subject: Re: [Patch V8] i2c: imx: add runtime pm support to improve the performance
Date: Sat, 10 Oct 2015 08:30:21 +0100 [thread overview]
Message-ID: <20151010073020.GB1619@katana> (raw)
In-Reply-To: <1442569869-10584-1-git-send-email-b54642@freescale.com>
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On Fri, Sep 18, 2015 at 05:51:09PM +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.
>
> 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>
Uwe? Sascha?
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next prev parent reply other threads:[~2015-10-10 7:30 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-18 9:51 [Patch V8] i2c: imx: add runtime pm support to improve the performance Gao Pan
2015-09-25 9:36 ` Gao Pandy
2015-10-10 7:30 ` Wolfram Sang [this message]
2015-10-13 7:07 ` Uwe Kleine-König
2015-10-13 9:08 ` Gao Pandy
2015-10-15 17:03 ` Shubhrajyoti Datta
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