Date: Sun, 08 Jul 2012 13:28:28 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: Taku YAMAMOTO <taku@tackymt.homeip.net> Cc: "freebsd-acpi@freebsd.org" <freebsd-acpi@FreeBSD.org> Subject: Re: disabled CST_CNT write Message-ID: <4FF960CC.1080909@FreeBSD.org> In-Reply-To: <20120708191937.46148f65.taku@tackymt.homeip.net> References: <4FF94EC4.1060109@FreeBSD.org> <20120708191937.46148f65.taku@tackymt.homeip.net>
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on 08/07/2012 13:19 Taku YAMAMOTO said the following: > On Sun, 08 Jul 2012 12:11:32 +0300 > Andriy Gapon <avg@FreeBSD.org> wrote: > >> >> acpi_cpu.c has a block of code to write CST_CNT to SMI_CMD, but the block is >> under #ifdef notyet. It seems that the code was added that many years ago and >> never enabled. >> Now, judging from the reports I've seen on this mailing list, it appears that >> _CST changes do happen and the driver seem to handle them sufficiently well. >> I think that a lot of modern platforms do not even provide CST_CNT and assume >> that an OS is able to handle C-state change notifications. >> So, I guess that it should be safe to enable the code in question now. >> >> Could anyone with a FreeBSD laptop and non-zero CST_CNT in FADT please test this? > > My Thinkpad X60 (Core 2 Duo) is such one of them. > Enabling that code makes this laptop correctly raise _CST change > notification on AC status change without a single problem. > Without enabling that, this laptop never generates such notifications. > > In fact, I have been enabling that code locally for more than a couple of > years without a problem :) > > In addition, that does not interfere with jkim's acpi_cx_native2.diff; > I've been enjoying MWAIT C3 with varying sleep depth based upon AC availability. > Thank you very much for the information! I will commit this change. -- Andriy Gapon
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