Hello, 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) };
