linux-kernel - Re: [PATCH v1] PM: sleep: core: Synchronize runtime PM status of parents and children

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Message-ID: <Z5nnaU5VnDK9yNTW@hovoldconsulting.com>
Date: Wed, 29 Jan 2025 09:31:37 +0100
From: Johan Hovold <johan@...nel.org>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc: Linux PM <linux-pm@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Bjorn Helgaas <helgaas@...nel.org>,
	Linux PCI <linux-pci@...r.kernel.org>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Kevin Xie <kevin.xie@...rfivetech.com>
Subject: Re: [PATCH v1] PM: sleep: core: Synchronize runtime PM status of
 parents and children

On Tue, Jan 28, 2025 at 08:24:41PM +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> Commit 6e176bf8d461 ("PM: sleep: core: Do not skip callbacks in the
> resume phase") overlooked the case in which the parent of a device with
> DPM_FLAG_SMART_SUSPEND set did not use that flag and could be runtime-
> suspended before a transition into a system-wide sleep state.  In that
> case, if the child is resumed during the subsequent transition from
> that state into the working state, its runtime PM status will be set to
> RPM_ACTIVE, but the runtime PM status of the parent will not be updated
> accordingly, even though the parent will be resumed too, because of the
> dev_pm_skip_suspend() check in device_resume_noirq().
> 
> Address this problem by tracking the need to set the runtime PM status
> to RPM_ACTIVE during system-wide resume transitions for devices with
> DPM_FLAG_SMART_SUSPEND set and all of the devices depended on by them.
> 
> Fixes: 6e176bf8d461 ("PM: sleep: core: Do not skip callbacks in the resume phase")
> Closes: https://lore.kernel.org/linux-pm/Z30p2Etwf3F2AUvD@hovoldconsulting.com/
> Reported-by: Johan Hovold <johan@...nel.org>
> Tested-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Thanks for tracking this down Mani, and thanks Rafael for the quick fix.

As expected this makes the warning go away also in my setup, and the
patch itself looks correct to me:

Reviewed-by: Johan Hovold <johan+linaro@...nel.org>
Tested-by: Johan Hovold <johan+linaro@...nel.org>

Johan