From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Nikula Subject: Re: [PATCH] i2c/designware: enable i2c controller to suspend/resume asynchronously Date: Tue, 5 Jan 2016 10:53:35 +0200 Message-ID: <568B848F.1070801@linux.intel.com> References: <567C0192.2050601@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <567C0192.2050601@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org To: "Fu, Zhonghui" , Andy Shevchenko , Mika Westerberg , Wolfram Sang Cc: linux-i2c@vger.kernel.org, "linux-kernel@vger.kernel.org" , srinivas.kowtal@intel.com List-Id: linux-i2c@vger.kernel.org Hi On 12/24/2015 04:30 PM, 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. > Nice reduction :-) > diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c > index 6b00061..395130b 100644 > --- a/drivers/i2c/busses/i2c-designware-platdrv.c > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c > @@ -230,6 +230,7 @@ static int dw_i2c_plat_probe(struct platform_device *pdev) > } > > adap = &dev->adapter; > + device_enable_async_suspend(&pdev->dev); > adap->owner = THIS_MODULE; > adap->class = I2C_CLASS_DEPRECATED; > ACPI_COMPANION_SET(&adap->dev, ACPI_COMPANION(&pdev->dev)); Does device_enable_async_suspend() need to be called before enabling runtime PM? I suppose not since there appears to have also related sysfs node for toggling it runtime. I'm thinking if you could move the device_enable_async_suspend() call into drivers/i2c/busses/i2c-designware-core.c: i2c_dw_probe() and then also PCI enumerated adapter could take advantage of it. -- Jarkko