On Mon, Dec 11, 2017 at 05:52:16PM +0100, Hans de Goede wrote: > 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 <hdego...@redhat.com>
Applied to libata/for-4.16. Thanks, Hans. -- tejun
