diff options
| author | Hans de Goede <hdegoede@redhat.com> | 2017-09-14 12:35:36 +0200 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2017-09-18 20:22:04 -0700 |
| commit | f4ac6476945ff62939420bcf8266e39f8d5d54bd (patch) | |
| tree | 3428a2c2eeff5f7e8f63949914246add64721a90 /include/linux/libata.h | |
| parent | 23e4c67ae13da7549a54f4e8c0014f48b2ef5204 (diff) | |
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: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'include/linux/libata.h')
| -rw-r--r-- | include/linux/libata.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/libata.h b/include/linux/libata.h index 931c32f1f18d..ed9826b21c5e 100644 --- a/include/linux/libata.h +++ b/include/linux/libata.h @@ -522,6 +522,7 @@ enum ata_lpm_policy { ATA_LPM_UNKNOWN, ATA_LPM_MAX_POWER, ATA_LPM_MED_POWER, + ATA_LPM_MED_POWER_WITH_DIPM, /* Med power + DIPM as win IRST does */ ATA_LPM_MIN_POWER, }; |