libata-pmp-prep: implement ATA_HORKAGE_SKIP_PM

Some pseudo devices fail PM commands unnecessarily aborting system
suspend.  Implement ATA_HORKAGE_SKIP_PM which makes libata skip PM
commands for these devices.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

2 files changed, 8 insertions, 0 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 8ca2caeed017..451f79c6fbac 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -944,6 +944,13 @@ static unsigned int ata_scsi_start_stop_xlat(struct ata_queued_cmd *qc)
                 goto invalid_fld;       /* LOEJ bit set not supported */
         if (((cdb[4] >> 4) & 0xf) != 0)
                 goto invalid_fld;       /* power conditions not supported */
+
+        if (qc->dev->horkage & ATA_HORKAGE_SKIP_PM) {
+                /* the device lacks PM support, finish without doing anything */
+                scmd->result = SAM_STAT_GOOD;
+                return 1;
+        }
+
         if (cdb[4] & 0x1) {
                 tf->nsect = 1;  /* 1 sector, lba=0 */
 
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 2bd1d26c9c8d..56b218771114 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -329,6 +329,7 @@ enum {
         ATA_HORKAGE_NONCQ       = (1 << 2),     /* Don't use NCQ */
         ATA_HORKAGE_MAX_SEC_128 = (1 << 3),     /* Limit max sects to 128 */
         ATA_HORKAGE_BROKEN_HPA  = (1 << 4),     /* Broken HPA */
+        ATA_HORKAGE_SKIP_PM     = (1 << 5),     /* Skip PM operations */
 };
 
 enum hsm_task_states {