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authorHans de Goede <hdegoede@redhat.com>2017-12-11 17:52:16 +0100
committerTejun Heo <tj@kernel.org>2017-12-11 08:53:33 -0800
commitebb82e3c79d2a956366d0848304a53648bd6350b (patch)
tree3894ee6113c2d3beeebb1b71b61284c988935f18 /drivers/ata/ahci.h
parent998008b779e424bd7513c434d0ab9c1268459009 (diff)
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/ahci.h')
-rw-r--r--drivers/ata/ahci.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index 749fd94441b0..a9d996e17d75 100644
--- a/drivers/ata/ahci.h
+++ b/drivers/ata/ahci.h
@@ -251,6 +251,9 @@ enum {
AHCI_HFLAG_YES_ALPM = (1 << 23), /* force ALPM cap on */
AHCI_HFLAG_NO_WRITE_TO_RO = (1 << 24), /* don't write to read
only registers */
+ AHCI_HFLAG_IS_MOBILE = (1 << 25), /* mobile chipset, use
+ SATA_MOBILE_LPM_POLICY
+ as default lpm_policy */
/* ap->flags bits */

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