Re: [PATCH v1] PM: runtime: Update last_busy in rpm_resume() for active devices

[Brian Norris <briannorris@chromium.org>]

On Fri, Nov 06, 2026 at 12:31:41PM +0100, Rafael J. Wysocki wrote:
> From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> 
> Setting an autosuspend delay for a device can be expected to cause a
> runtime suspend of the device after calling, say, pm_runtime_put() to
> be deferred, so the time between the last successful attempt to resume
> the device and its subsequent suspend is at least equal to the
> autosuspend delay.
> 
> However, that expectation is only met after the device has been actually
> resumed in rpm_resume() by invoking its runtime resume callback.  If the
> runtime PM status of the device is already "active" when rpm_resume()
> runs for it, the device's last_busy timestamp is not updated which may
> allow a subsequent pm_runtime_put() invocation (or similar) to suspend
> it right away.
> 
> This is arguably inconsistent and confusing, so make rpm_resume() also
> update the device's last_busy timestamp when it finds that the device is
> already "active" and it is about to return 1 early.
> 
> Fixes: 56f487c78015 ("PM / Runtime: Update last_busy in rpm_resume")
> Link: https://lore.kernel.org/linux-pm/CAJZ5v0jTX1FgeS9FCV=+V4uacSgLQBVsSPnU27ybgUGg57GUOA@mail.gmail.com/
> Reported-by: Brian Norris <briannorris@chromium.org>

Ha, I suppose you can call it Reported-by, even if it's somewhat of a
tangent IMO :)

> Cc: All applicable <stable@vger.kernel.org>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Reviewed-by: Brian Norris <briannorris@chromium.org>
Tested-by: Brian Norris <briannorris@chromium.org>