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Subject[PATCH] Driver core: leave runtime PM enabled during system shutdown
Disabling all runtime PM during system shutdown turns out not to be a
good idea, because some devices may need to be woken up from a
low-power state at that time.

The whole point of disabling runtime PM for system shutdown was to
prevent untimely runtime-suspend method calls. This patch (as1504)
accomplishes the same result by incrementing the usage count for each
device and waiting for ongoing runtime-PM callbacks to finish. This
is what we already do during system suspend and hibernation, which
makes sense since the shutdown method is pretty much a legacy analog
of the pm->poweroff method.

This fixes a regression on some OMAP systems.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: NeilBrown <neilb@suse.de>
CC: Chen Peter-B29397 <B29397@freescale.com>

---
drivers/base/core.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
Index: usb-3.2/drivers/base/core.c
===================================================================
--- usb-3.2.orig/drivers/base/core.c
+++ usb-3.2/drivers/base/core.c
@@ -1743,8 +1743,10 @@ void device_shutdown(void)
*/
list_del_init(&dev->kobj.entry);
spin_unlock(&devices_kset->list_lock);
- /* Disable all device's runtime power management */
- pm_runtime_disable(dev);
+
+ /* Don't allow any more runtime suspends */
+ pm_runtime_get_noresume(dev);
+ pm_runtime_barrier(dev);

if (dev->bus && dev->bus->shutdown) {
dev_dbg(dev, "shutdown\n");


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