From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752102AbcAEMOJ (ORCPT ); Tue, 5 Jan 2016 07:14:09 -0500 Received: from mga01.intel.com ([192.55.52.88]:53884 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751608AbcAEMOG (ORCPT ); Tue, 5 Jan 2016 07:14:06 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,525,1444719600"; d="scan'208";a="853855928" Message-ID: <1451996056.30729.394.camel@linux.intel.com> Subject: Re: [PATCH] i2c/designware: enable i2c controller to suspend/resume asynchronously From: Andy Shevchenko To: Jarkko Nikula , "Fu, Zhonghui" , Mika Westerberg , Wolfram Sang Cc: linux-i2c@vger.kernel.org, "linux-kernel@vger.kernel.org" , srinivas.kowtal@intel.com Date: Tue, 05 Jan 2016 14:14:16 +0200 In-Reply-To: <568B848F.1070801@linux.intel.com> References: <567C0192.2050601@linux.intel.com> <568B848F.1070801@linux.intel.com> Organization: Intel Finland Oy Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.18.2-1 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2016-01-05 at 10:53 +0200, Jarkko Nikula wrote: > 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. I concern about Intel BayTrail-T / Braswell / CherryTrail cases, since we have non-trivial PM for LPSS there. Zhonghui, have you a chance to stress test this on platforms based on mentioned SoCs? -- Andy Shevchenko Intel Finland Oy