* AHCI power down unused ports merge status?
@ 2008-09-27 19:39 Jeffrey W. Baker
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From: Jeffrey W. Baker @ 2008-09-27 19:39 UTC (permalink / raw)
To: linux-ide
I was just poking around in the ICH8 documentation and /dev/mem and I
notice that all three of the SATA PHYs on my laptop are enabled, when I
have only one SATA target device. AHCI allows the port to be disabled,
and this saves a lot of power, but this functionality is not exposed in
Linux.
There are patches floating around on this mailing list to disable the
port by echoing "power_off" to ALPM in sysfs, but this patch isn't
merged in libata-dev and I don't see it in 2.6.27-rc7 either. Is there
any hope of this getting merged? Is it dangerous or otherwise not
advised?
I think users would really appreciate having this. Disabling unused
ports results in +10% extra battery life on my laptop.
cf http://marc.info/?l=linux-ide&m=121504056904748&w=2
I think part 1 is severable from part 2, so perhaps the sysfs bits can
be merged without the default policy part that seems objectionable.
-jwb
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