From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932985AbZJOCus (ORCPT ); Wed, 14 Oct 2009 22:50:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758804AbZJOCus (ORCPT ); Wed, 14 Oct 2009 22:50:48 -0400 Received: from thunk.org ([69.25.196.29]:51700 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754615AbZJOCur (ORCPT ); Wed, 14 Oct 2009 22:50:47 -0400 Date: Wed, 14 Oct 2009 22:26:45 -0400 From: Theodore Tso To: Jesse Barnes Cc: "Carlos R. Mafra" , Eric Anholt , linux-kernel@vger.kernel.org, Keith Packard , Chris Wilson Subject: Re: 2.6.32 regression (bisected): Video tearing/glitching with T400 laptops Message-ID: <20091015022645.GA8286@mit.edu> Mail-Followup-To: Theodore Tso , Jesse Barnes , "Carlos R. Mafra" , Eric Anholt , linux-kernel@vger.kernel.org, Keith Packard , Chris Wilson References: <20091008103620.5e5aae66@jbarnes-g45> <20091010204106.GA8251@mit.edu> <20091012095438.1e82b54f@jbarnes-g45> <20091012184651.GA4603@Pilar.aei.mpg.de> <20091012120510.16bd1194@jbarnes-g45> <20091013023146.GA8414@mit.edu> <20091013100135.2b3d914f@jbarnes-g45> <20091013190055.GI8175@mit.edu> <20091013121426.35f409ff@jbarnes-g45> <20091014142252.009d03a5@jbarnes-g45> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091014142252.009d03a5@jbarnes-g45> User-Agent: Mutt/1.5.18 (2008-05-17) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@mit.edu X-SA-Exim-Scanned: No (on thunker.thunk.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 14, 2009 at 02:22:52PM -0700, Jesse Barnes wrote: > On Tue, 13 Oct 2009 12:14:26 -0700 > Jesse Barnes wrote: > > According to the chipset team that form of display corruption is > > likely related to RAM self-refresh... Sounds like the display plane > > isn't getting its memory requests serviced fast enough when in > > self-refresh mode, which might mean we have to program the > > self-refresh watermarks more aggressively on GM45. > > Ok, like any good bug there was more than one thing wrong: > - we weren't setting up a fence for the object before enabling FBC. > Chris caught this and posted a patch to > intel-gfx@lists.freedesktop.org titled "drm/i915: Install a fence > register for fbc on g4x" (attached for convenience) > - turns out we *do* need to set watermarks on G4x, despite some hw > documentation indicating otherwise, patch for that attached > > Hopefully with these two you'll have a solid display and some power > saving! With these two patches (and none of your prior ones) applied to 2.6.32-rc3, things are definitely better. I'm still seeing a few glitches (one as mutt was loading my Maildir inbox) and one as I was typing this message in emacs, but it's at best one minor every 5-10 minutes. It's rare enough to be at most a wee bit distracting (*lots* better than before), and I can see the power savings. If I need to live with a display glitch every 5-10 minutes or so to get better power savings, I'll take it.... - Ted