On Mon, 2016-02-01 at 17:04 +0200, Jarkko Nikula wrote: > On 01/15/2016 08:38 AM, Fu, Zhonghui wrote: > > Now, PM core supports asynchronous suspend/resume mode for devices > > during system suspend/resume, and the power state transition of one > > device may be completed in separate kernel thread. PM core ensures > > all power state transition dependency between devices. This patch > > enables designware i2c controllers to suspend/resume > > asynchronously. > > This will take advantage of multicore and improve system > > suspend/resume > > speed. After enabling all i2c devices, i2c adapters and i2c > > controllers > > on ASUS T100TA tablet, the system suspend-to-idle time is reduced > > to > > about 510ms from 750ms, and the system resume time is reduced to > > about > > 790ms from 900ms. > > > > Signed-off-by: Zhonghui Fu <zhonghui.fu@xxxxxxxxxxxxxxx> > > --- > > Changes in v2: > > - Move the device_enable_async_suspend() call into i2c_dw_proble() > > > > drivers/i2c/busses/i2c-designware-core.c | 1 + > > 1 files changed, 1 insertions(+), 0 deletions(-) > > > > diff --git a/drivers/i2c/busses/i2c-designware-core.c > > b/drivers/i2c/busses/i2c-designware-core.c > > index ba9732c..5d6ad27 100644 > > --- a/drivers/i2c/busses/i2c-designware-core.c > > +++ b/drivers/i2c/busses/i2c-designware-core.c > > @@ -861,6 +861,7 @@ int i2c_dw_probe(struct dw_i2c_dev *dev) > > > > init_completion(&dev->cmd_complete); > > mutex_init(&dev->lock); > > + device_enable_async_suspend(dev->dev); > > > I'm aware Andy had concerns about about stability and you also > mention > in another thread: > > "if enable all LPSS devices suspend/resume asynchronously, the > system > can't resume sometimes on ASUS T100TA(BayTrail-T SoC). But, I have > verified that the system can resume normally every time if enable > only > i2c controller async mode and let other LPSS devices in sync mode on > ASUS T100TA.". > > What I'm thinking would this change move things forward and help to > find > out what potential underlying issues there are in LPSS code. > > I'm fine with this I2C side change but can we assure we don't > accidentally enable the same on other LPSS devices before finding > the > root cause for the crash? Besides that we have to be really aware about DMA power related fix introduced in v4.5-rc1 in acpi_lpss.c [1]. So, I would like to see a wide testing especially on Intel Baytrail / Braswell platforms before enabling it. [1] http://comments.gmane.org/gmane.linux.acpi.devel/80263 -- Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Intel Finland Oy -- 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
