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@xxxxxxxxxxxxx> > Signed-off-by: Gao Pan <b54642@xxxxxxxxxxxxx> > Acked-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> Applied to for-next, thanks! Also much thanks to Uwe and Heiner for the reviews of all these versions!
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