From: linux-i2c-owner@xxxxxxxxxxxxxxx <mailto:linux-i2c-owner@xxxxxxxxxxxxxxx> On Behalf Of Uwe Kleine-K?nig Sent: Tuesday, September 08, 2015 5:18 AM > To: Gao Pan-B54642 > Cc: wsa@xxxxxxxxxxxxx; linux-i2c@xxxxxxxxxxxxxxx; Li Frank-B20596; Duan > Fugang-B38611; kernel@xxxxxxxxxxxxxx; hkallweit1@xxxxxxxxx > Subject: Re: [Patch V7] i2c: imx: add runtime pm support to improve the > performance > > Hello, > > On Mon, Aug 31, 2015 at 03:32:33PM +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@xxxxxxxxxxxxx> > > Signed-off-by: Gao Pan <b54642@xxxxxxxxxxxxx> > > [wsa: fixed some indentation] > > Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxxxxx> > Hmm, why does this already have a S-o-b from Wolfram? > > Other than that I don't have any caveats to enter any more, but given > that I don't have much clue about runtime pm this doesn't mean much. Thank you, I unintentionally added Wolfram to the S-o-b. This patch was accepted after Wolfram fixed some indentation by V3. Afterwards, Heiner Kallweit found some problems. So the following versions mainly resolve the problems found by Heiner Kallweit. I will resend the this patch with S-o-b from Wolfram deleted. > Best regards > Uwe > > -- > Pengutronix e.K. | Uwe Kleine-König > | > Industrial Linux Solutions | http://www.pengutronix.de/ > | > -- > To unsubscribe from this list: send the line "unsubscribe linux-i2c" in > the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at > http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
