[PATCH v2 0/2] fixes for ata port runtime pm support

[PATCH v2 0/2] fixes for ata port runtime pm support

[Lin Ming]

Hi Jeff,

Here are the v2 fixes for ata port runtime pm support.
Applied on top of linux-next-20111214 tree.

Changes in v2:
- Drop the patch "[SCSI] sd: fix runtime status check in sd_shutdown".
  It's no longer needed with commit fe6b91f(PM / Driver core: leave
  runtime PM enabled during system shutdown).
- Add Ack from Alan

v1: https://lkml.org/lkml/2011/12/13/443

Lin Ming (2):
      [SCSI]: runtime resume parent for child's system-resume
      ata: update ata port's runtime status during system resume

 drivers/ata/libata-core.c |   18 ++++++++++++++++--
 drivers/scsi/scsi_pm.c    |   11 ++++++++++-
 2 files changed, 26 insertions(+), 3 deletions(-)

Thanks,
Lin Ming

[PATCH v2 1/2] [SCSI]: runtime resume parent for child's system-resume

[Lin Ming]

[Patch description from Alan Stern]

If a child device was runtime-suspended when a system suspend began,
then there will be nothing to prevent its parent from
runtime-suspending as soon as it is woken up during the system resume.
Then when the time comes to resume the child, the resume will fail
because the parent is already back at low power.

On the other hand, there are some devices which should remain at low
power across an entire suspend-resume cycle.  The details depend on the
device and the platform.

This suggests that the PM core is not the right place to solve the
problem. One possible solution is for the subsystem or device driver
to call pm_runtime_get_sync(dev->parent) at the start of the
system-resume procedure and pm_runtime_put_sync(dev->parent) at the
end.

Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
---
 drivers/scsi/scsi_pm.c |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/drivers/scsi/scsi_pm.c b/drivers/scsi/scsi_pm.c
index a633076..bf8bf79 100644
--- a/drivers/scsi/scsi_pm.c
+++ b/drivers/scsi/scsi_pm.c
@@ -72,8 +72,17 @@ static int scsi_bus_resume_common(struct device *dev)
 {
 	int err = 0;
 
-	if (scsi_is_sdev_device(dev))
+	if (scsi_is_sdev_device(dev)) {
+		/*
+		 * Parent device may have runtime suspended as soon as
+		 * it is woken up during the system resume.
+		 *
+		 * Resume it on behalf of child.
+		 */
+		pm_runtime_get_sync(dev->parent);
 		err = scsi_dev_type_resume(dev);
+		pm_runtime_put_sync(dev->parent);
+	}
 
 	if (err == 0) {
 		pm_runtime_disable(dev);
-- 
1.7.2.5

[PATCH v2 2/2] ata: update ata port's runtime status during system resume

[Lin Ming]

The ata port is brought back to full power state during system resume.
So its runtime PM status will have to be updated to reflect
the actual post-system sleep status.

This also fixes below warning during system suspend/resume.

WARNING: at /work/linux/drivers/ata/libata-eh.c:4034
ata_scsi_port_error_handler+0x89/0x557()

4034         WARN_ON(!(ap->pflags & ATA_PFLAG_SUSPENDED));

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
---
 drivers/ata/libata-core.c |   18 ++++++++++++++++--
 1 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 15a3d4d..8996758 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -5298,7 +5298,7 @@ static int ata_port_suspend(struct device *dev)
 	return ata_port_suspend_common(dev);
 }
 
-static int ata_port_resume(struct device *dev)
+static int ata_port_resume_common(struct device *dev)
 {
 	struct ata_port *ap = to_ata_port(dev);
 	int rc;
@@ -5308,6 +5308,20 @@ static int ata_port_resume(struct device *dev)
 	return rc;
 }
 
+static int ata_port_resume(struct device *dev)
+{
+	int rc;
+
+	rc = ata_port_resume_common(dev);
+	if (!rc) {
+		pm_runtime_disable(dev);
+		pm_runtime_set_active(dev);
+		pm_runtime_enable(dev);
+	}
+
+	return rc;
+}
+
 static int ata_port_runtime_idle(struct device *dev)
 {
 	return pm_runtime_suspend(dev);
@@ -5318,7 +5332,7 @@ static const struct dev_pm_ops ata_port_pm_ops = {
 	.resume = ata_port_resume,
 
 	.runtime_suspend = ata_port_suspend_common,
-	.runtime_resume = ata_port_resume,
+	.runtime_resume = ata_port_resume_common,
 	.runtime_idle = ata_port_runtime_idle,
 };
 
-- 
1.7.2.5