From f4ac6476945ff62939420bcf8266e39f8d5d54bd Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Thu, 14 Sep 2017 12:35:36 +0200 Subject: 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 Cc: Matthew Garrett Signed-off-by: Hans de Goede Signed-off-by: Tejun Heo --- include/linux/libata.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/libata.h') 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, }; -- cgit v1.2.3