Commit f4ac6476 authored by Hans de Goede's avatar Hans de Goede Committed by Tejun Heo

libata: Add new med_power_with_dipm link_power_management_policy setting

As described by Matthew Garret quite a while back:
https://mjg59.dreamwidth.org/34868.html

Intel CPUs starting with the Haswell generation need SATA links to power
down for the "package" part of the CPU to reach low power-states like
PC7 / P8 which bring a significant power-saving with them.

The default max_performance lpm policy does not allow for these high
PC states, both the medium_power and min_power policies do allow this.

The min_power policy saves significantly more power, but there are some
reports of some disks / SSDs not liking min_power leading to system
crashes and in some cases even data corruption has been reported.

Matthew has found a document documenting the default settings of
Intel's IRST Windows driver with which most laptops ship:
https://www-ssl.intel.com/content/dam/doc/reference-guide/sata-devices-implementation-recommendations.pdf

Matthew wrote a patch changing med_power to match those defaults, but
that never got anywhere as some people where reporting issues with the
patch-set that patch was a part of.

This commit is another attempt to make the default IRST driver settings
available under Linux, but instead of changing medium_power and
potentially introducing regressions, this commit adds a new
med_power_with_dipm setting which is identical to the existing
medium_power accept that it enables dipm on top, which makes it match
the Windows IRST driver settings, which should hopefully be safe to
use on most devices.

The med_power_with_dipm setting is close to min_power, except that:
a) It does not use host-initiated slumber mode (ASP not set),
   but it does allow device-initiated slumber
b) It does not enable DevSlp mode

On my T440s test laptop I get the following power savings when idle:
medium_power		0.9W
med_power_with_dipm	1.2W
min_power		1.2W
Suggested-by: default avatarMatthew Garrett <mjg59@srcf.ucam.org>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 23e4c67a
...@@ -3964,6 +3964,7 @@ int sata_link_scr_lpm(struct ata_link *link, enum ata_lpm_policy policy, ...@@ -3964,6 +3964,7 @@ int sata_link_scr_lpm(struct ata_link *link, enum ata_lpm_policy policy,
scontrol &= ~(0x1 << 8); scontrol &= ~(0x1 << 8);
scontrol |= (0x6 << 8); scontrol |= (0x6 << 8);
break; break;
case ATA_LPM_MED_POWER_WITH_DIPM:
case ATA_LPM_MIN_POWER: case ATA_LPM_MIN_POWER:
if (ata_link_nr_enabled(link) > 0) if (ata_link_nr_enabled(link) > 0)
/* no restrictions on LPM transitions */ /* no restrictions on LPM transitions */
......
...@@ -3454,9 +3454,9 @@ static int ata_eh_maybe_retry_flush(struct ata_device *dev) ...@@ -3454,9 +3454,9 @@ static int ata_eh_maybe_retry_flush(struct ata_device *dev)
* @r_failed_dev: out parameter for failed device * @r_failed_dev: out parameter for failed device
* *
* Enable SATA Interface power management. This will enable * Enable SATA Interface power management. This will enable
* Device Interface Power Management (DIPM) for min_power * Device Interface Power Management (DIPM) for min_power and
* policy, and then call driver specific callbacks for * medium_power_with_dipm policies, and then call driver specific
* enabling Host Initiated Power management. * callbacks for enabling Host Initiated Power management.
* *
* LOCKING: * LOCKING:
* EH context. * EH context.
...@@ -3502,7 +3502,7 @@ static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy, ...@@ -3502,7 +3502,7 @@ static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
hints &= ~ATA_LPM_HIPM; hints &= ~ATA_LPM_HIPM;
/* disable DIPM before changing link config */ /* disable DIPM before changing link config */
if (policy != ATA_LPM_MIN_POWER && dipm) { if (policy < ATA_LPM_MED_POWER_WITH_DIPM && dipm) {
err_mask = ata_dev_set_feature(dev, err_mask = ata_dev_set_feature(dev,
SETFEATURES_SATA_DISABLE, SATA_DIPM); SETFEATURES_SATA_DISABLE, SATA_DIPM);
if (err_mask && err_mask != AC_ERR_DEV) { if (err_mask && err_mask != AC_ERR_DEV) {
...@@ -3545,7 +3545,7 @@ static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy, ...@@ -3545,7 +3545,7 @@ static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
/* host config updated, enable DIPM if transitioning to MIN_POWER */ /* host config updated, enable DIPM if transitioning to MIN_POWER */
ata_for_each_dev(dev, link, ENABLED) { ata_for_each_dev(dev, link, ENABLED) {
if (policy == ATA_LPM_MIN_POWER && !no_dipm && if (policy >= ATA_LPM_MED_POWER_WITH_DIPM && !no_dipm &&
ata_id_has_dipm(dev->id)) { ata_id_has_dipm(dev->id)) {
err_mask = ata_dev_set_feature(dev, err_mask = ata_dev_set_feature(dev,
SETFEATURES_SATA_ENABLE, SATA_DIPM); SETFEATURES_SATA_ENABLE, SATA_DIPM);
......
...@@ -106,10 +106,11 @@ static const u8 def_control_mpage[CONTROL_MPAGE_LEN] = { ...@@ -106,10 +106,11 @@ static const u8 def_control_mpage[CONTROL_MPAGE_LEN] = {
}; };
static const char *ata_lpm_policy_names[] = { static const char *ata_lpm_policy_names[] = {
[ATA_LPM_UNKNOWN] = "max_performance", [ATA_LPM_UNKNOWN] = "max_performance",
[ATA_LPM_MAX_POWER] = "max_performance", [ATA_LPM_MAX_POWER] = "max_performance",
[ATA_LPM_MED_POWER] = "medium_power", [ATA_LPM_MED_POWER] = "medium_power",
[ATA_LPM_MIN_POWER] = "min_power", [ATA_LPM_MED_POWER_WITH_DIPM] = "med_power_with_dipm",
[ATA_LPM_MIN_POWER] = "min_power",
}; };
static ssize_t ata_scsi_lpm_store(struct device *device, static ssize_t ata_scsi_lpm_store(struct device *device,
......
...@@ -522,6 +522,7 @@ enum ata_lpm_policy { ...@@ -522,6 +522,7 @@ enum ata_lpm_policy {
ATA_LPM_UNKNOWN, ATA_LPM_UNKNOWN,
ATA_LPM_MAX_POWER, ATA_LPM_MAX_POWER,
ATA_LPM_MED_POWER, ATA_LPM_MED_POWER,
ATA_LPM_MED_POWER_WITH_DIPM, /* Med power + DIPM as win IRST does */
ATA_LPM_MIN_POWER, ATA_LPM_MIN_POWER,
}; };
......
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