From mboxrd@z Thu Jan  1 00:00:00 1970
From: Daniel Vetter <daniel@ffwll.ch>
Subject: Re: [PATCH 00/13] Gen7 batch buffer command parser
Date: Thu, 30 Jan 2014 00:31:53 +0100
Message-ID: <20140129233152.GE17001@phenom.ffwll.local>
References: <1385484699-51596-1-git-send-email-bradley.d.volkin@intel.com>
	<1391032514-19136-1-git-send-email-bradley.d.volkin@intel.com>
	<20140129221117.GD17001@phenom.ffwll.local>
	<20140129222249.GA19431@vpg-ubuntu-bdvolkin>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <intel-gfx-bounces@lists.freedesktop.org>
Received: from mail-ea0-f169.google.com (mail-ea0-f169.google.com
	[209.85.215.169])
	by gabe.freedesktop.org (Postfix) with ESMTP id 6771C44CB7
	for <intel-gfx@lists.freedesktop.org>;
	Wed, 29 Jan 2014 15:31:58 -0800 (PST)
Received: by mail-ea0-f169.google.com with SMTP id h10so1270462eak.14
	for <intel-gfx@lists.freedesktop.org>;
	Wed, 29 Jan 2014 15:31:57 -0800 (PST)
Content-Disposition: inline
In-Reply-To: <20140129222249.GA19431@vpg-ubuntu-bdvolkin>
List-Unsubscribe: <http://lists.freedesktop.org/mailman/options/intel-gfx>,
	<mailto:intel-gfx-request@lists.freedesktop.org?subject=unsubscribe>
List-Archive: <http://lists.freedesktop.org/archives/intel-gfx>
List-Post: <mailto:intel-gfx@lists.freedesktop.org>
List-Help: <mailto:intel-gfx-request@lists.freedesktop.org?subject=help>
List-Subscribe: <http://lists.freedesktop.org/mailman/listinfo/intel-gfx>,
	<mailto:intel-gfx-request@lists.freedesktop.org?subject=subscribe>
Sender: intel-gfx-bounces@lists.freedesktop.org
Errors-To: intel-gfx-bounces@lists.freedesktop.org
To: "Volkin, Bradley D" <bradley.d.volkin@intel.com>
Cc: "intel-gfx@lists.freedesktop.org" <intel-gfx@lists.freedesktop.org>
List-Id: intel-gfx@lists.freedesktop.org

On Wed, Jan 29, 2014 at 02:22:49PM -0800, Volkin, Bradley D wrote:
> On Wed, Jan 29, 2014 at 02:11:17PM -0800, Daniel Vetter wrote:
> > On Wed, Jan 29, 2014 at 01:55:01PM -0800, bradley.d.volkin@intel.com wrote:
> > > From: Brad Volkin <bradley.d.volkin@intel.com>
> > > 3) Coherency. I've found a coherency issue on VLV when reading the batch buffer
> > >    from the CPU during execbuffer2. Userspace writes the batch via pwrite fast
> > >    path before calling execbuffer2. The parser reads stale data. This works fine
> > >    on IVB and HSW, so I believe it's an LLC vs. non-LLC issue. I'm just unclear
> > >    on what the correct flushing or synchronization is for this scenario. This
> > >    only matters if we get PPGTT working on VLV and enable the parser there.
> > 
> > Hm, adopting the shmem_read clflushing didn't help for this? That would be
> > fairly shocking, since it means our shmem read paths are broken. Which are
> > used e.g. by the libva readback code for the encoded bitstream.
> 
> Sorry, not clear enough. I actually haven't retested that part with the clflushing
> added since the opinion seemed to be that leaving the parser disabled for VLV was ok.
> Just left the note for now so it doesn't get lost.

Would be nice to give it spin though, since afaik this issue might persist
on vlv+1. And I guess we can't keep on sticking our heads into sand about
ppgtt not really working on soc platforms ;-)
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch