From mboxrd@z Thu Jan 1 00:00:00 1970 From: Borislav Petkov Subject: Re: [PATCH] x86/ACPI/cstate: Allow ACPI C1 FFH MWAIT use on AMD systems Date: Tue, 23 May 2017 15:06:16 +0200 Message-ID: <20170523130616.GC25383@nazgul.tnic> References: <1495030819-4347-1-git-send-email-Yazen.Ghannam@amd.com> <20170522162143.GA19781@nazgul.tnic> <20170523075911.GA25383@nazgul.tnic> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Received: from mail.skyhub.de ([5.9.137.197]:43666 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750987AbdEWNGU (ORCPT ); Tue, 23 May 2017 09:06:20 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: "Ghannam, Yazen" Cc: "linux-pm@vger.kernel.org" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , "rjw@rjwysocki.net" , "len.brown@intel.com" , "pavel@ucw.cz" On Tue, May 23, 2017 at 12:50:15PM +0000, Ghannam, Yazen wrote: > No, AMD systems will continue to use HLT unless the BIOS specifies the > use of MWAIT using a FFH entry in the ACPI _CST. > > All this change does is *allow* us to use MWAIT through the FFH > implementation if the BIOS defines it. It doesn't *force* a change. So that could very well be part of the commit message as it explains what exactly you're changing. > If the BIOS doesn't define the appropriate _CST entry or it defines it > wrong, then we'll fallback to using HLT. I'm assuming you've tested it on older families to make sure they still work as expected? I wouldn't trust the BIOS... -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. --