From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752526AbeCYLuw (ORCPT ); Sun, 25 Mar 2018 07:50:52 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:43711 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752004AbeCYLuv (ORCPT ); Sun, 25 Mar 2018 07:50:51 -0400 Date: Sun, 25 Mar 2018 13:50:40 +0200 (CEST) From: Thomas Gleixner To: Anshuman Gupta cc: glx@linutronix.de, x86@kernel.org, mingo@redhat.com, hpa@zytor.com, rjw@rjwysocki.net, andriy.shevchenko@linux.intel.com, alan@linux.intel.com, linux-kernel@vger.kernel.org, rajneesh.bhardwaj@intel.com Subject: Re: [PATCH v3] x86: i8237: Register based on FADT legacy boot flag In-Reply-To: <1521714118-31282-1-git-send-email-anshuman.gupta@intel.com> Message-ID: References: <1521714118-31282-1-git-send-email-anshuman.gupta@intel.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 22 Mar 2018, Anshuman Gupta wrote: > From: Rajneesh Bhardwaj > > >From Skylake onwards, the platform controller hub (Sunrisepoint PCH) does > not support legacy DMA operations to IO ports 81h-83h, 87h, 89h-8Bh, 8Fh. > Currently this driver registers as syscore ops and its resume function is > called on every resume from S3. On Skylake and Kabylake, this causes a > resume delay of around 100ms due to port IO operations, which is a problem. > > This change allows to load the driver only when the platform bios > explicitly supports such devices or has a cut-off date earlier than 2017. Please explain WHY 2017 is the cut-off date. I still have no clue how that is decided aside of being a random number. Thanks, tglx