On 21 April 2016 at 23:07, Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote: > Hi Rafael, > > On Thursday 21 Apr 2016 23:02:06 Rafael J. Wysocki wrote: >> On Thu, Apr 21, 2016 at 10:57 PM, Laurent Pinchart wrote: >> > On Thursday 21 Apr 2016 21:52:56 Rafael J. Wysocki wrote: >> >> On Thursday, April 21, 2016 02:52:55 AM Laurent Pinchart wrote: >> >>> The pm_runtime_force_suspend() and pm_runtime_force_resume() helpers >> >>> are designed to help driver being RPM-centric by offering an easy way to >> >>> manage runtime PM state during system suspend and resume. The first >> >>> function will force the device into runtime suspend at system suspend >> >>> time, while the second one will perform the reverse operation at system >> >>> resume time. >> >>> >> >>> However, the pm_runtime_force_resume() really forces resume, regardless >> >>> of whether the device was running or already suspended before the call >> >>> to pm_runtime_force_suspend(). This results in devices being runtime >> >>> resumed at system resume time when they shouldn't. >> >>> >> >>> Fix this by recording whether the device has been forcefully suspended >> >>> in pm_runtime_force_suspend() and condition resume in >> >>> pm_runtime_force_resume() to that state. >> >>> >> >>> All current users of pm_runtime_force_resume() call the function >> >>> unconditionally in their system resume handler (some actually set it as >> >>> the resume handler), all after calling pm_runtime_force_suspend() at >> >>> system suspend time. The change in behaviour should thus be safe. >> >>> >> >>> Signed-off-by: Laurent Pinchart >> >>> <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx> >> >>> Reviewed-by: Kevin Hilman <khilman@xxxxxxxxxxxx> >> >> >> >> Ulf, any comments? >> > >> > Ulf has proposed a different approach in "[PATCH] PM / Runtime: Defer >> > resuming of the device in pm_runtime_force_resume()". I agree that using >> > usage_count is better than introducing a new state flag in struct >> > dev_pm_info, with a caveat: it doesn't work properly :-). We would have >> > to fix genpd first, as commented in a reply to Ulf's patch. >> >> OK, thanks! >> >> Since I'd prefer to avoid adding more state flags too, I'll let you >> guys noodle around this for a while more. :-) > > Let's see what we can do in a reasonable time frame. We could decide to merge > this patch as a temporary fix until the genpd rework is complete. Subsystems/driver that uses pm_runtime_force_suspend|resume() don't necessarily need to have their devices attached to a genpd. In such cases, $subject patch will be an improvement by itself. Me personally would rather skip the intermediate step you propose, as I prefer to properly change genpd with what is needed. Moreover, I am already working on that so it shouldn't take too long before I can post some patches. Kind regards Uffe
