On Tuesday, August 29, 2017 5:05:20 PM CEST Ulf Hansson wrote: > On 29 August 2017 at 16:43, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote: > > On Tuesday, August 29, 2017 1:44:11 PM CEST Ulf Hansson wrote: > >> On 29 August 2017 at 12:29, Johannes Stezenbach <js@xxxxxxxxx> wrote: > >> > Hi, > >> > > >> > On Tue, Aug 29, 2017 at 02:18:13AM +0200, Rafael J. Wysocki wrote: > >> >> On Wednesday, August 23, 2017 4:42:00 PM CEST Ulf Hansson wrote: > >> >> > The i2c designware platform driver, drivers/i2c/busses/i2c-designware-platdrv.c, > >> >> > isn't well optimized for system sleep. > >> >> > > >> >> > What makes this driver particularly interesting is because it's a cross-SoC > >> >> > driver, which sometimes means there is an ACPI PM domain attached to the i2c > >> >> > device and sometimes not. The driver is being used on both x86 and ARM. > >> > ... > >> >> Basically, the point is to allow i2c-designware-platdrv to point its late > >> >> suspend and early resume callbacks, respectively, to pm_runtime_force_suspend() > >> >> and pm_runtime_force_resume() which then will do the right thing regardless of > >> >> whether or not the device is runtime suspended when system suspend starts. > >> > > >> > I'd like to point out a comment added by Hans de Goede in > >> > https://bugzilla.kernel.org/show_bug.cgi?id=193891#c99 > >> > > >> > The D0 / D3 methods of some devices use ACPI OpRegions on the PMIC which is > >> > attached to I2C7, these methods get executed by acpi_dev_suspend_late / > >> > acpi_dev_resume_early. Since the i2c-designware driver uses regular suspend / > >> > resume callbacks it is already suspended at the time those calls happen, > >> > leading to a device-suspend error and the system not suspending at all. > >> > >> Yes, that's why I moved those operation to be managed at the > >> ->suspend_late() in my series, and at the same time prevent the > >> direct_complete patch from executed for this device. > >> > >> > > >> > It's the reason for the Cherrytrail I2C7 special treatment in > >> > i2c-designware-platdrv.c and pm_disabled = true in i2c-designware-baytrail.c, > >> > however pm_disabled seems to be a problem for S0ix support. > >> > To solve it, i2c-designware-platdrv needs to suspend after all > >> > devices using ACPI OpRegions for suspend. > >> > > >> > > >> > Johannes > >> > >> Did you try out my series (v2) if that could fix this problem in a > >> more flexible manner? > >> > >> In other words, is it fine if the device remains runtime PM enabled > >> during the entire device_suspend() phase, and also not being suspended > >> until ->suspend_late()? > > > > Ulf, please, this is a *different* problem. > > Yes, it is! > > Just wanted to point out that if the device remains runtime PM enabled > the entire device_suspend() phase, that *could* solve the problem. > > > > > Can we focus on one problem at a time? > > Yes! > > However, there is lots of things following when we try to enable the > runtime PM centric path for ACPI. :-) Which, I guess, we won't do after all ... So I would prefer to think about addressing problems instead of trying to "enable the runtime PM centric path for ACPI" just for the sake of it. Thanks, Rafael
