From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel 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: Content-Disposition: inline In-Reply-To: <20150929092714.GD9460-AwZRO8vwLAwmlAP/+Wk3EA@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Thierry Reding Cc: Tomasz Figa , iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Hiroshi Doyu , Stephen Warren , Alexandre Courbot , Vince Hsu , Russell King , Paul Walmsley , Tomeu Vizoso , Mikko Perttunen , Will Deacon , Alex Williamson , Arnd Bergmann , Marek Szyprowski , Antonios Motakis , Olav Haugan , Nicolas Iooss , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: iommu@lists.linux-foundation.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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756276AbbI2MWj (ORCPT ); Tue, 29 Sep 2015 08:22:39 -0400 Received: from 8bytes.org ([81.169.241.247]:53617 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752812AbbI2MWd (ORCPT ); Tue, 29 Sep 2015 08:22:33 -0400 Date: Tue, 29 Sep 2015 14:22:32 +0200 From: Joerg Roedel To: Thierry Reding Cc: Tomasz Figa , iommu@lists.linux-foundation.org, Hiroshi Doyu , Stephen Warren , Alexandre Courbot , Vince Hsu , Russell King , Paul Walmsley , Tomeu Vizoso , Mikko Perttunen , Will Deacon , Alex Williamson , Arnd Bergmann , Marek Szyprowski , Antonios Motakis , Olav Haugan , Nicolas Iooss , linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org Subject: Re: [RFC PATCH 0/3] iommu: Add range flush operation 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 Content-Disposition: inline In-Reply-To: <20150929092714.GD9460@ulmo.nvidia.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@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