From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Wilson Subject: Re: [PATCH] drm/i915: Don't forget to apply SNB PIPE_CONTROL GTT workaround. Date: Tue, 31 Jul 2012 09:21:55 +0100 Message-ID: <1343722926_20786@CP5-2952> References: <1343697866-5572-1-git-send-email-eric@anholt.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from fireflyinternet.com (smtp.fireflyinternet.com [109.228.6.236]) by gabe.freedesktop.org (Postfix) with ESMTP id A6FD89E7BF for ; Tue, 31 Jul 2012 01:22:10 -0700 (PDT) In-Reply-To: <1343697866-5572-1-git-send-email-eric@anholt.net> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: Eric Anholt , intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org On Mon, 30 Jul 2012 18:24:26 -0700, Eric Anholt wrote: > If a buffer that was the target of a PIPE_CONTROL from userland was a > reused one that hadn't been evicted which had not previously had this > workaround applied, then we would not bind it into the GTT and the > write would land somewhere else. > > Based on a doubting-my-sanity debugging session with cworth, I'm > pretty sure this will fix his reproducible GL_EXT_timer_query > failures, and hopefully the intermittent OQ issues on snb that > danvet's been working on. > > I have not tested it yet, but hopefully when cworth gets home he will. Had to look hard to find the secret ingredient. The reason why this patch will work is that that in the middle of the error checking we have an early success return after applying the new reloc domains iff the object still holds the same GTT offset as presumed by the reloc. Probably deserves a little more clarification in the changelog as to why the patch works. Reviewed-by: Chris Wilson I think this should also fix https://bugs.freedesktop.org/show_bug.cgi?id=48019 but my snb has decided today is the day to hard hang instead. -Chris -- Chris Wilson, Intel Open Source Technology Centre