On Tue, Jun 26, 2018 at 12:06:01PM +0200, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > It is reported that commit c62ec4610c40 (PM / core: Fix direct_complete > handling for devices with no callbacks) introduced a system suspend > regression on Samsung 305V4A by allowing a PCI bridge (not a PCIe > port) to stay in D3 over suspend-to-RAM, which is a side effect of > setting power.direct_complete for the children of that bridge that > have no PM callbacks. > > On the majority of systems PCI bridges are not allowed to be > runtime-suspended (the power/control sysfs attribute is set to "on" > for them by default), but user space can change that setting and if > it does so and a given bridge has no children with PM callbacks, the > direct_complete optimization will be applied to it and it will stay > in suspend over system suspend. Apparently, that confuses the > platform firmware on the affected machine and that may very well > happen elsewhere, so avoid the direct_complete optimization for > PCI bridges with no drivers (if there is a driver, it should take > care of the PM handling) on suspend-to-RAM altogether (that should > not matter for suspend-to-idle as platform firmware is not involved > in it). > > Fixes: c62ec4610c40 (PM / core: Fix direct_complete handling for devices with no callbacks) > Link: https://bugzilla.kernel.org/show_bug.cgi?id=199941 > Reported-by: n0000b.n000b@xxxxxxxxx > Tested-by: n0000b.n000b@xxxxxxxxx > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
