scsi: sd: Differentiate system and runtime start/stop management

The underlying device and driver of a SCSI disk may have different
system and runtime power mode control requirements. This is because
runtime power management affects only the SCSI disk, while system level
power management affects all devices, including the controller for the
SCSI disk.

For instance, issuing a START STOP UNIT command when a SCSI disk is
runtime suspended and resumed is fine: the command is translated to a
STANDBY IMMEDIATE command to spin down the ATA disk and to a VERIFY
command to wake it up. The SCSI disk runtime operations have no effect
on the ata port device used to connect the ATA disk. However, for
system suspend/resume operations, the ATA port used to connect the
device will also be suspended and resumed, with the resume operation
requiring re-validating the device link and the device itself. In this
case, issuing a VERIFY command to spinup the disk must be done before
starting to revalidate the device, when the ata port is being resumed.
In such case, we must not allow the SCSI disk driver to issue START STOP
UNIT commands.

Allow a low level driver to refine the SCSI disk start/stop management
by differentiating system and runtime cases with two new SCSI device
flags: manage_system_start_stop and manage_runtime_start_stop. These new
flags replace the current manage_start_stop flag. Drivers setting the
manage_start_stop are modifed to set both new flags, thus preserving the
existing start/stop management behavior. For backward compatibility, the
old manage_start_stop sysfs device attribute is kept as a read-only
attribute showing a value of 1 for devices enabling both new flags and 0
otherwise.

Fixes: 0a8589055936 ("ata,scsi: do not issue START STOP UNIT on resume")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/firewire/sbp2.c b/drivers/firewire/sbp2.c
index 26db5b8dfc1ef..749868b9e80d6 100644
--- a/drivers/firewire/sbp2.c
+++ b/drivers/firewire/sbp2.c
@@ -81,7 +81,8 @@ MODULE_PARM_DESC(exclusive_login, "Exclusive login to sbp2 device "
  *
  * - power condition
  *   Set the power condition field in the START STOP UNIT commands sent by
- *   sd_mod on suspend, resume, and shutdown (if manage_start_stop is on).
+ *   sd_mod on suspend, resume, and shutdown (if manage_system_start_stop or
+ *   manage_runtime_start_stop is on).
  *   Some disks need this to spin down or to resume properly.
  *
  * - override internal blacklist
@@ -1517,8 +1518,10 @@ static int sbp2_scsi_slave_configure(struct scsi_device *sdev)
 
 	sdev->use_10_for_rw = 1;
 
-	if (sbp2_param_exclusive_login)
-		sdev->manage_start_stop = 1;
+	if (sbp2_param_exclusive_login) {
+		sdev->manage_system_start_stop = true;
+		sdev->manage_runtime_start_stop = true;
+	}
 
 	if (sdev->type == TYPE_ROM)
 		sdev->use_10_for_ms = 1;