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| author | Hans de Goede <hdegoede@redhat.com> | 2017-12-11 17:52:16 +0100 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2017-12-11 08:53:33 -0800 |
| commit | ebb82e3c79d2a956366d0848304a53648bd6350b (patch) | |
| tree | 3894ee6113c2d3beeebb1b71b61284c988935f18 /crypto/api.c | |
| parent | 998008b779e424bd7513c434d0ab9c1268459009 (diff) | |
| download | linux-ebb82e3c79d2a956366d0848304a53648bd6350b.tar.bz2 | |
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 'crypto/api.c')
0 files changed, 0 insertions, 0 deletions