From mboxrd@z Thu Jan  1 00:00:00 1970
From: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
Subject: Re: [RFC PATCH 0/3] iommu: Add range flush operation
Date: Tue, 29 Sep 2015 14:22:32 +0200
Message-ID: <20150929122232.GH3036@8bytes.org>
References: <1443504379-31841-1-git-send-email-tfiga@chromium.org>
 <20150929092714.GD9460@ulmo.nvidia.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Return-path: <linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Content-Disposition: inline
In-Reply-To: <20150929092714.GD9460-AwZRO8vwLAwmlAP/+Wk3EA@public.gmane.org>
Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
To: Thierry Reding <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Tomasz Figa <tfiga-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Hiroshi Doyu <hdoyu-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>, Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>, Alexandre Courbot <gnurou-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Vince Hsu <vince.h-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>, Russell King <rmk+kernel-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>, Paul Walmsley <paul-DWxLp4Yu+b8AvxtiuMwx3w@public.gmane.org>, Tomeu Vizoso <tomeu.vizoso-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>, Mikko Perttunen <mperttunen-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>, Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>, Alex Williamson <alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>, Marek Szyprowski <m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>, Antonios Motakis <a.motakis-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org>, Olav Haugan <ohaugan-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>, Nicolas Iooss <nicolas.iooss_linux-oWGTIYur0i8@public.gmane.org>, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
List-Id: linux-tegra@vger.kernel.org

On Tue, Sep 29, 2015 at 11:27:14AM +0200, Thierry Reding wrote:
> On Tue, Sep 29, 2015 at 02:25:23PM +0900, Tomasz Figa wrote:
> >  3) possibility of exporting the iommu_flush() operation and providing
> >     unsynchronized map/unmap operations for subsystems with even higher
> >     requirements for performance (e.g. drivers/gpu/drm).
> 
> That would require passing in some sort of flag that the core shouldn't
> be flushing itself, right? Currently it would flush on every map/unmap.

Not necessarily. Introducing a flag would require updating all callers,
so while at it we could also just change the semantics of map/unmap to
require an explicit flush afterwards (only if it turns out that such an
iommu_flush() function is really needed).



	Joerg