On 12/19/23 18:15, Thomas Richard wrote: > Hello, I add some people in this thread. > > I have a gpio expander (pca953x driver) connected to an i2c controller > managed by the omap-i2c driver. > And I have some issues with pm_runtime_force_suspend/resume during > suspend to ram. > For some reasons, related to hardware design, I need to access to this > gpio expander during suspend_noirq and resume_noirq. So I had to move > the suspend/resume of the pca953x to suspend_noirq/resume_noirq. > > The i2c controller is autosuspended when I start the suspend sequence. > In suspend_noirq, I access to one gpio of the expander, so rpm_resume is > called to resume the i2c controller. > And rpm_resume returns an error because disable_depth > 0 [1]. In > suspend_noirq, runtime pm is disabled (disable_depth is incremented when > runtime pm is disabled [2]). So the expander is not reachable, and the > access fails. > > [1] > https://elixir.bootlin.com/linux/v6.7-rc6/source/drivers/base/power/runtime.c#L773 > [2] > https://elixir.bootlin.com/linux/v6.7-rc6/source/drivers/base/power/runtime.c#L1474 > > The suspend_noirq of the gpio expander don't do i2c access, so no > problem for pca953x suspend. > The pm_runtime_force_suspend (suspend_noirq [3]) of the i2c controller > does nothing as the device is already suspended [4]. > > [3] > https://elixir.bootlin.com/linux/v6.7-rc6/source/drivers/i2c/busses/i2c-omap.c#L1579 > [4] > https://elixir.bootlin.com/linux/v6.7-rc6/source/drivers/base/power/runtime.c#L1878 > > Then during the pm_runtime_force_resume (resume_noirq [3]) the i2c > controller is not resumed because needs_for_resume is equal to 0 [5]. > The needs_for_resume flag is set in pm_runtime_force_suspend [6] but we > don't reach this point, because the device is already suspended [4]. > > [5] > https://elixir.bootlin.com/linux/v6.7-rc6/source/drivers/base/power/runtime.c#L1929 > [6] > https://elixir.bootlin.com/linux/v6.7-rc6/source/drivers/base/power/runtime.c#L1900 > > Then the resume_noirq of the pca953x driver is called, consequently > rpm_resume is called to resume the i2c controller. But it is never > resumed because disable_depth > 0 [7] (runtime pm is still disabled in > resume_noirq). So the resume_noirq fails. > > [7] > https://elixir.bootlin.com/linux/v6.7-rc6/source/drivers/base/power/runtime.c#L773 > > I found a workaround which is to resume the controller and disable > runtime pm during suspend, then runtime pm is enabled during resume. > But there is probably a better solution to fix this issue. > > Best Regards, > > Thomas Richard > > > diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c > index 42165ef57946..fe79b27b46fd 100644 > --- a/drivers/i2c/busses/i2c-omap.c > +++ b/drivers/i2c/busses/i2c-omap.c > @@ -1575,9 +1575,24 @@ static int __maybe_unused > omap_i2c_runtime_resume(struct device *dev) > return 0; > } > > +static int omap_i2c_suspend(struct device *dev) > +{ > + pm_runtime_get_sync(dev); > + pm_runtime_disable(dev); > + return 0; > +} > + > +static int omap_i2c_resume(struct device *dev) > +{ > + pm_runtime_enable(dev); > + pm_runtime_put_autosuspend(dev); > + return 0; > +} > + > static const struct dev_pm_ops omap_i2c_pm_ops = { > SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, > pm_runtime_force_resume) > + SET_SYSTEM_SLEEP_PM_OPS(omap_i2c_suspend, omap_i2c_resume) > SET_RUNTIME_PM_OPS(omap_i2c_runtime_suspend, > omap_i2c_runtime_resume, NULL) > }; > > > -- Thomas Richard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
