PM: Allow SCSI devices to suspend/resume asynchronously

Set power.async_suspend for all SCSI devices, targets and hosts, so
that they can be suspended and resumed in parallel with the main
suspend/resume thread and possibly with other devices they don't
depend on in a known way (i.e. devices which are not their parents or
children).

The power.async_suspend flag is also set for devices that don't have
suspend or resume callbacks, because otherwise they would make the
main suspend/resume thread wait for their "asynchronous" children
(during suspend) or parents (during resume), effectively negating the
possible gains from executing these devices' suspend and resume
callbacks asynchronously.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 554626e18062..09dbcb847b73 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -215,6 +215,8 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
                 shost->shost_gendev.parent = dev ? dev : &platform_bus;
         shost->dma_dev = dma_dev;
 
+        device_enable_async_suspend(&shost->shost_gendev);
+
         error = device_add(&shost->shost_gendev);
         if (error)
                 goto out;
@@ -222,6 +224,8 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
         scsi_host_set_state(shost, SHOST_RUNNING);
         get_device(shost->shost_gendev.parent);
 
+        device_enable_async_suspend(&shost->shost_dev);
+
         error = device_add(&shost->shost_dev);
         if (error)
                 goto out_del_gendev;