From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: Re: [PATCH] drm/i915: Workaround incoherence with fence updates on Valleyview Date: Wed, 22 May 2013 20:33:27 +0200 Message-ID: <20130522183327.GD1082@phenom.ffwll.local> References: <1369238887-9528-1-git-send-email-chris@chris-wilson.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-wg0-f44.google.com (mail-wg0-f44.google.com [74.125.82.44]) by gabe.freedesktop.org (Postfix) with ESMTP id 6E178E5E16 for ; Wed, 22 May 2013 11:33:32 -0700 (PDT) Received: by mail-wg0-f44.google.com with SMTP id a12so1478095wgh.11 for ; Wed, 22 May 2013 11:33:31 -0700 (PDT) Content-Disposition: inline In-Reply-To: <1369238887-9528-1-git-send-email-chris@chris-wilson.co.uk> 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: Chris Wilson Cc: intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org On Wed, May 22, 2013 at 05:08:06PM +0100, Chris Wilson wrote: > In commit 25ff1195f8a0b3724541ae7bbe331b4296de9c06 > Author: Chris Wilson > Date: Thu Apr 4 21:31:03 2013 +0100 > > drm/i915: Workaround incoherence between fences and LLC across multiple CPUs > > we introduced an empirical workaround for memory corruption when using > fences from multiple CPUs. At the time, we did not have any results for > Valleyview, so the presumption was that it was limited to recent > generations using LLC. Now we have evidence that Valleyview also suffers > incoherence and requires a similar but different workaround. For > Valleyview, the wbinvd instruction is insufficient and we require the > serialising register write per-CPU. Conversely, that serialising > register write is not enough for SNB/IVB/HSW. To compromise and keep the > code relatively clean, employ both serialisation techniques in the same > workaround. > > Reported-by: Jon Bloomfield > Tested-by: Jon Bloomfield > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=62191 > Signed-off-by: Chris Wilson Queued for -next (since vlv isn't yet declared stable in 3.10), thanks for the patch. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch