On Sat, 02 Feb 2013 21:50:35 +0100 "Rafael J. Wysocki" <rjw at sisk.pl> wrote: > > > + * Drivers can indicate support for switchless suspend/resume, which can > > > + * save time and flicker, by using this routine and passing 'false' as > > > + * the argument. If any loaded driver needs VT switching, or the > > > + * no_console_suspend argument has been passed on the command line, VT > > > + * switches will occur. > > > + */ > > > > It seems to me that we'll need a separate counter for the number of registered > > drivers and do the switch if that number is equal to the number of drivers that > > have passed false to this thing. > > > > In which case we can simplify this slightly and introduce > > pm_vt_swtich_not_required(void) > > Sorry, that won't be sufficient. Rather something like pm_vt_switch_get() > (indicating "I'll do the switch, thanks") and pm_vt_switch_put() (indicating > "now you need to do the switch yourself"). I thought of both of your approaches before posting this one, but each have other problems. And I found a bug in mine last night. So I think I need a separate count of drivers that need the switch, and ones that don't. Then if either no driver has registered or if the need_switch count is nonzero, we'll do the switch. Otherwise, if the dont_need_switch is nonzero, we can avoid the switch. I think that'll handle all the cases I outlined. My code as posted will fail if one driver needs a switch but then two switch free drivers register. Jesse
