From ebb82e3c79d2a956366d0848304a53648bd6350b Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Mon, 11 Dec 2017 17:52:16 +0100 Subject: 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 Signed-off-by: Tejun Heo --- drivers/ata/Kconfig | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'drivers/ata/Kconfig') 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 -- cgit