On Tue, 28 Jun 2011, Rafael J. Wysocki wrote: > On Tuesday, June 28, 2011, Ming Lei wrote: > > > > Hi Rafael, > > > > On Sun, 26 Jun 2011 00:56:31 +0200 > > "Rafael J. Wysocki" <rjw@xxxxxxx> wrote: > > > > > Index: linux-2.6/Documentation/power/runtime_pm.txt > > > =================================================================== > > > --- linux-2.6.orig/Documentation/power/runtime_pm.txt > > > +++ linux-2.6/Documentation/power/runtime_pm.txt > > > @@ -567,6 +567,11 @@ this is: > > > pm_runtime_set_active(dev); > > > pm_runtime_enable(dev); > > > > > > +The PM core always increments the run-time usage counter before calling the > > > +->suspend() callback and decrements it after calling the ->resume() callback. > > > +Hence disabling run-time PM temporarily like this will not cause any run-time > > > +suspend callbacks to be lost. > > > > Could you explain why the above is that "this will not cause any run-time suspend > > callbacks to be lost"? > > > > Looks like it should be "this will not cause any run-time suspend callbacks to > > be called", but not sure. > > You're right the wording is not perfect. The problem is that if it's done > this way without incrementing the usage counter beforehand, the status may > change to "suspended" right before the pm_runtime_set_active() and then the > new status will not reflect the actual state of the device. > > So, it may be better to say "Hence disabling runtime PM temporarily like this > will not cause the runtime PM status of the device to conflict with the actual > device state". > > Alan, what do you think? How about: "... will not cause any runtime suspend attempts to be permanently lost. If the usage count goes to zero following the return of the ->resume() callback, the ->runtime_idle() callback will be invoked as usual." Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
