Date: Wed, 17 Nov 2004 12:27:36 -0800 From: Nate Lawson <nate@root.org> To: Andrey Smirnov <smir@delit.net> Cc: freebsd-acpi@freebsd.org Subject: Re: Why C3 state isn't entered? Message-ID: <419BB438.3040906@root.org> In-Reply-To: <419BB14C.1060301@delit.net> References: <419BB14C.1060301@delit.net>
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Andrey Smirnov wrote: > Hello! > > I've got Centrino notebook (specifically Asus M3700Np), and it doesn't > seem to enter C3 sleep state in any case. > Sample output from 'sysctl hw.acpi.cpu' (while working at battery): > > hw.acpi.cpu.cx_supported: C1/0 C2/1 C3/101 > hw.acpi.cpu.cx_lowest: C3 > hw.acpi.cpu.cx_usage: 0.00% 100.00% 0.00% > > So C3 is supported, is allowed but isn't entered according to cx_usage. > Why could it be so? > > My system: > bash-2.05b$ uname -a > FreeBSD smira.mlab.cs.msu.su 6.0-CURRENT FreeBSD 6.0-CURRENT #1: Wed Oct > 13 13:50:01 MSD 2004 > root@smira.mlab.cs.msu.su:/usr/src/sys/i386/compile/smira.mobile i386 > > acpidump -d -t output, bzipped: > http://images.delit.net/acpidump.asl.bz2 This is a FAQ, perhaps we can add it to the handbook entry or man page: C3 can't be entered while bus masters are active. Typical bus mastering devices include USB and sound. Since USB constantly polls when loaded, disabling USB support or stopping sound playback should allow C3 to be used. A better fix would be to power down the USB host controller when idle. -Nate
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