ahci: implement aggressive SATA device sleep support

Device Sleep is a feature as described in AHCI 1.3.1 Technical Proposal.
This feature enables an HBA and SATA storage device to enter the DevSleep
interface state, enabling lower power SATA-based systems.

Aggressive Device Sleep enables the HBA to assert the DEVSLP signal as
soon as there are no commands outstanding to the device and the port
specific Device Sleep idle timer has expired. This enables autonomous
entry into the DevSleep interface state without waiting for software
in power sensitive systems.

This patch enables Aggressive Device Sleep only if both host controller
and device support it.

Tested on AMD reference board together with Device Sleep supported device
sample.

Signed-off-by: Shane Huang <shane.huang@amd.com>
Reviewed-by: Aaron Lu <aaron.lwe@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 24 insertions, 5 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 5eee1c1537d..25daf39368f 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -2155,6 +2155,7 @@ int ata_dev_configure(struct ata_device *dev)
 	int print_info = ehc->i.flags & ATA_EHI_PRINTINFO;
 	const u16 *id = dev->id;
 	unsigned long xfer_mask;
+	unsigned int err_mask;
 	char revbuf[7];		/* XYZ-99\0 */
 	char fwrevbuf[ATA_ID_FW_REV_LEN+1];
 	char modelbuf[ATA_ID_PROD_LEN+1];
@@ -2323,6 +2324,26 @@ int ata_dev_configure(struct ata_device *dev)
 			}
 		}
 
+		/* check and mark DevSlp capability */
+		if (ata_id_has_devslp(dev->id))
+			dev->flags |= ATA_DFLAG_DEVSLP;
+
+		/* Obtain SATA Settings page from Identify Device Data Log,
+		 * which contains DevSlp timing variables etc.
+		 * Exclude old devices with ata_id_has_ncq()
+		 */
+		if (ata_id_has_ncq(dev->id)) {
+			err_mask = ata_read_log_page(dev,
+						     ATA_LOG_SATA_ID_DEV_DATA,
+						     ATA_LOG_SATA_SETTINGS,
+						     dev->sata_settings,
+						     1);
+			if (err_mask)
+				ata_dev_dbg(dev,
+					    "failed to get Identify Device Data, Emask 0x%x\n",
+					    err_mask);
+		}
+
 		dev->cdb_len = 16;
 	}
 
@@ -2351,8 +2372,6 @@ int ata_dev_configure(struct ata_device *dev)
 		    (ap->flags & ATA_FLAG_AN) && ata_id_has_atapi_AN(id) &&
 		    (!sata_pmp_attached(ap) ||
 		     sata_scr_read(&ap->link, SCR_NOTIFICATION, &sntf) == 0)) {
-			unsigned int err_mask;
-
 			/* issue SET feature command to turn this on */
 			err_mask = ata_dev_set_feature(dev,
 					SETFEATURES_SATA_ENABLE, SATA_AN);
@@ -3598,7 +3617,7 @@ int sata_link_scr_lpm(struct ata_link *link, enum ata_lpm_policy policy,
 	switch (policy) {
 	case ATA_LPM_MAX_POWER:
 		/* disable all LPM transitions */
-		scontrol |= (0x3 << 8);
+		scontrol |= (0x7 << 8);
 		/* initiate transition to active state */
 		if (spm_wakeup) {
 			scontrol |= (0x4 << 12);
@@ -3608,12 +3627,12 @@ int sata_link_scr_lpm(struct ata_link *link, enum ata_lpm_policy policy,
 	case ATA_LPM_MED_POWER:
 		/* allow LPM to PARTIAL */
 		scontrol &= ~(0x1 << 8);
-		scontrol |= (0x2 << 8);
+		scontrol |= (0x6 << 8);
 		break;
 	case ATA_LPM_MIN_POWER:
 		if (ata_link_nr_enabled(link) > 0)
 			/* no restrictions on LPM transitions */
-			scontrol &= ~(0x3 << 8);
+			scontrol &= ~(0x7 << 8);
 		else {
 			/* empty port, power off */
 			scontrol &= ~0xf;