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authorHans de Goede <hdegoede@redhat.com>2017-12-11 19:52:16 +0300
committerTejun Heo <tj@kernel.org>2017-12-11 19:53:33 +0300
commitebb82e3c79d2a956366d0848304a53648bd6350b (patch)
tree3894ee6113c2d3beeebb1b71b61284c988935f18 /drivers/ata/Kconfig
parent998008b779e424bd7513c434d0ab9c1268459009 (diff)
downloadlinux-ebb82e3c79d2a956366d0848304a53648bd6350b.tar.xz
ahci: Allow setting a default LPM policy for mobile chipsets
On many laptops setting a different LPM policy then unknown / max_performance can lead to power-savings of 1.0 - 1.5 Watts (when idle). Modern ultrabooks idle around 6W (at 50% screen brightness), 1.0 - 1.5W is a significant chunk of this. There are some performance / latency costs to enabling LPM by default, so it is desirable to make it possible to set a different LPM policy for mobile / laptop variants of chipsets / "South Bridges" vs their desktop / server counterparts. Also enabling LPM by default is not entirely without risk of regressions. At least min_power is known to cause issues with some disks, including some reports of data corruption. This commits adds a new ahci.mobile_lpm_policy kernel cmdline option, which defaults to a new SATA_MOBILE_LPM_POLICY Kconfig option so that Linux distributions can choose to set a LPM policy for mobile chipsets by default. The reason to have both a kernel cmdline option and a Kconfig default value for it, is to allow easy overriding of the default to allow trouble-shooting without needing to rebuild the kernel. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'drivers/ata/Kconfig')
-rw-r--r--drivers/ata/Kconfig19
1 files changed, 19 insertions, 0 deletions
diff --git a/drivers/ata/Kconfig b/drivers/ata/Kconfig
index cb5339166563..b3fad5663aeb 100644
--- a/drivers/ata/Kconfig
+++ b/drivers/ata/Kconfig
@@ -92,6 +92,25 @@ config SATA_AHCI
If unsure, say N.
+config SATA_MOBILE_LPM_POLICY
+ int "Default SATA Link Power Management policy for mobile chipsets"
+ range 0 4
+ default 0
+ depends on SATA_AHCI
+ help
+ Select the Default SATA Link Power Management (LPM) policy to use
+ for mobile / laptop variants of chipsets / "South Bridges".
+
+ The value set has the following meanings:
+ 0 => Keep firmware settings
+ 1 => Maximum performance
+ 2 => Medium power
+ 3 => Medium power with Device Initiated PM enabled
+ 4 => Minimum power
+
+ Note "Minimum power" is known to cause issues, including disk
+ corruption, with some disks and should not be used.
+
config SATA_AHCI_PLATFORM
tristate "Platform AHCI SATA support"
help