From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754268Ab1K2RVd (ORCPT ); Tue, 29 Nov 2011 12:21:33 -0500 Received: from mail-fx0-f46.google.com ([209.85.161.46]:49092 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751944Ab1K2RVc (ORCPT ); Tue, 29 Nov 2011 12:21:32 -0500 Date: Tue, 29 Nov 2011 18:22:53 +0100 From: Daniel Vetter To: Chris Wilson , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, stable@kernel.org Subject: Re: [PATCH 2/2] drm/i915: properly clflush pwrites to phys objects Message-ID: <20111129172253.GD11090@phenom.ffwll.local> Mail-Followup-To: Chris Wilson , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, stable@kernel.org References: <1322579369-26954-1-git-send-email-daniel.vetter@ffwll.ch> <1322579369-26954-2-git-send-email-daniel.vetter@ffwll.ch> <20111129161652.GD5667@phenom.ffwll.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20111129161652.GD5667@phenom.ffwll.local> X-Operating-System: Linux phenom 3.1.0+ User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 29, 2011 at 05:16:52PM +0100, Daniel Vetter wrote: > On Tue, Nov 29, 2011 at 03:35:54PM +0000, Chris Wilson wrote: > > On Tue, 29 Nov 2011 16:09:29 +0100, Daniel Vetter wrote: > > > Usually results in (rare) cursor corruptions on platforms > > > requiring physically addressed cursors. > > > > So the phys cursor pages are set to WC upon creation, are we just > > missing the mb()? Or more likely the CPUs don't have PAT and we are > > being lazy in not detecting the error. > > Yes, on reconsidering the tested-by is from a pentium m, which has working > pat, and we do a wbinvd in the i8xx chipset flush, so I don't know anymore > how this patch actually works. > > But it seems to indeed fix the issue for at least one reporter and cursor > update is about as far away from a perf critical path as possible, so who > cares about such minor quibbles, it works ;-) After some irc discussion with Dave Airlie I'll now try whether a simple wmb(); to flush the wc cache isn't good enough. Will take at least a week to run by testers and gathe feedback, though. -Daniel -- Daniel Vetter Mail: daniel@ffwll.ch Mobile: +41 (0)79 365 57 48