[PATCH v3 01/10] ata: libata-core: Introduce ata_dev_config_lpm()

[Damien Le Moal <dlemoal@kernel.org>]

If the port of a device does not support Device Initiated Power
Management (DIPM), that is, the port is flagged with ATA_FLAG_NO_DIPM,
the DIPM feature of a device should not be used. Though DIPM is disabled
by default on a device, the "Software Settings Preservation feature"
may keep DIPM enabled or DIPM may have been enabled by the system
firmware.

Introduce the function ata_dev_config_lpm() to always disable DIPM on a
device that supports this feature if the port of the device is flagged
with ATA_FLAG_NO_DIPM. ata_dev_config_lpm() is called from
ata_dev_configure(), ensuring that a device DIPM feature is disabled
when it cannot be used.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/ata/libata-core.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 3918ea624e0b..6df5e51ece21 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -2790,6 +2790,30 @@ static void ata_dev_config_cpr(struct ata_device *dev)
 	kfree(buf);
 }
 
+/*
+ * Configure features related to link power management.
+ */
+static void ata_dev_config_lpm(struct ata_device *dev)
+{
+	struct ata_port *ap = dev->link->ap;
+	unsigned int err_mask;
+
+	/*
+	 * Device Initiated Power Management (DIPM) is normally disabled by
+	 * default on a device. However, DIPM may have been enabled and that
+	 * setting kept even after COMRESET because of the Software Settings
+	 * Preservation feature. So if the port does not support DIPM and the
+	 * device does, disable DIPM on the device.
+	 */
+	if (ap->flags & ATA_FLAG_NO_DIPM && ata_id_has_dipm(dev->id)) {
+		err_mask = ata_dev_set_feature(dev,
+					SETFEATURES_SATA_DISABLE, SATA_DIPM);
+		if (err_mask && err_mask != AC_ERR_DEV)
+			ata_dev_err(dev, "Disable DIPM failed, Emask 0x%x\n",
+				    err_mask);
+	}
+}
+
 static void ata_dev_print_features(struct ata_device *dev)
 {
 	if (!(dev->flags & ATA_DFLAG_FEATURES_MASK))
@@ -2963,6 +2987,7 @@ int ata_dev_configure(struct ata_device *dev)
 			ata_dev_config_chs(dev);
 		}
 
+		ata_dev_config_lpm(dev);
 		ata_dev_config_fua(dev);
 		ata_dev_config_devslp(dev);
 		ata_dev_config_sense_reporting(dev);
-- 
2.50.0