Date: Wed, 17 Jun 2009 16:10:25 +0300 From: Alexander Motin <mav@FreeBSD.org> To: Alexander Leidinger <Alexander@Leidinger.net> Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r191674 - in head/sys/dev/ata: . chipsets Message-ID: <4A38EB41.2080206@FreeBSD.org> In-Reply-To: <20090617150015.18455ggwluk5bcgs@webmail.leidinger.net> References: <200904292117.n3TLHIpt093110@svn.freebsd.org> <20090617150015.18455ggwluk5bcgs@webmail.leidinger.net>
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Alexander Leidinger wrote: > Quoting Alexander Motin <mav@FreeBSD.org> (from Wed, 29 Apr 2009 > 21:17:18 +0000 (UTC)): > >> Author: mav >> Date: Wed Apr 29 21:17:18 2009 >> New Revision: 191674 >> URL: http://svn.freebsd.org/changeset/base/191674 >> >> Log: >> Add experimental support for SATA interface power management. >> Feature is controlled by hint.ata.X.pm_level tunable: >> 0 - PM disabled, old behaviour, default. >> 1 - device is allowed to initiate PM state change, host is passive. >> 2 - host initiates PARTIAL state transition every time port is idle. >> 3 - host initiates SLUMBER state transition every time port is idle. > > Did I miss a man-page update for this? If yes, where is it, I would have > expected it in ata(4). There is none yet. >> PARTIAL state has up to 100us (50us for me) wakeup latency, but for my >> ICH8M saves 0.5W of power per drive. SLUMBER state has up to 10ms >> (3.5ms >> for me) wakeup latency, but saves 0.8W of power. >> >> Modes 2 and 3 are implemented only for AHCI driver now. > > Does this mean it is for SATA devices only, or is this a feature of the > complete controller (ICH5 in my case) and also works with PATA drives? This feature is SATA-specific by definition. AFAIK there is no bus power management in PATA. -- Alexander Motin
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