On Thu, 2011-11-24 at 01:02 +0800, Alan Stern wrote:
> On Wed, 23 Nov 2011, Lin Ming wrote:
>
> > From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> >
> > scsi device runtime PM is using PMSG_SUSPEND. System PM may use other state
> > that may not be compatiable with PMSG_SUSPEND.
>
> Actually SCSI runtime PM uses PMSG_AUTO_AUTOSUSPEND, which is the same
> as PMSG_SUSPEND except that the PM_EVENT_AUTO bit is also set in the
> pm_message.event field. Currently they _are_ compatible.
>
> > So we need to runtime resume the device before system suspend.
> >
> > Signed-off-by: Lin Ming <ming.m.lin@xxxxxxxxx>
> > ---
> >
> > Alan,
> >
> > Could you add your Signed-off-by?
> > Free free to change the commit logs.
>
> I don't know; this is a little questionable.
>
> The point of this patch is to handle drivers that do different things
> for runtime suspend and system sleep. The only SCSI driver that
> currently supports runtime suspend is sd, and it treats runtime suspend
> the same as system sleep. (Earlier I said it doesn't spin down disks
> for runtime suspend -- that was wrong, it does. It skips the spin-down
> step only for PM_EVENT_FREEZE, which is part of the hibernation
> procedure.)
>
> Until other SCSI drivers support runtime suspend, this patch shouldn't
> be needed. And spinning up runtime-suspended disks could add a lengthy
> delay to the system sleep transition, so it's better not to do this if
> at all possible.
For sd driver, PMSG_SUSPEND and PMSG_HIBERNATE are compatible with
PMSG_AUTO_SUSPEND. PMSG_FREEZE is not compatible.
So we only need to runtime resume sd for PMSG_FREEZE case.
How about below?
diff --git a/drivers/scsi/scsi_pm.c b/drivers/scsi/scsi_pm.c
index 549ea72..e2759d9 100644
--- a/drivers/scsi/scsi_pm.c
+++ b/drivers/scsi/scsi_pm.c
@@ -50,7 +50,13 @@ static int scsi_bus_suspend_common(struct device *dev, pm_message_t msg)
int err = 0;
if (scsi_is_sdev_device(dev)) {
- pm_runtime_resume(dev);
+ if (pm_runtime_suspended(dev)) {
+ if (msg.event == PM_EVENT_FREEZE)
+ pm_runtime_resume(dev);
+ else
+ return 0;
+ }
+
err = scsi_dev_type_suspend(dev, msg);
}
return err;
Lin Ming
>
> Alan Stern
>
> > drivers/scsi/scsi_pm.c | 4 +++-
> > 1 files changed, 3 insertions(+), 1 deletions(-)
> >
> > diff --git a/drivers/scsi/scsi_pm.c b/drivers/scsi/scsi_pm.c
> > index d329f8b..549ea72 100644
> > --- a/drivers/scsi/scsi_pm.c
> > +++ b/drivers/scsi/scsi_pm.c
> > @@ -49,8 +49,10 @@ static int scsi_bus_suspend_common(struct device *dev, pm_message_t msg)
> > {
> > int err = 0;
> >
> > - if (scsi_is_sdev_device(dev))
> > + if (scsi_is_sdev_device(dev)) {
> > + pm_runtime_resume(dev);
> > err = scsi_dev_type_suspend(dev, msg);
> > + }
> > return err;
> > }
>
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