From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Pinchart Subject: Re: [PATCH v5 11/18] iommu: exynos: remove useless device_add/remove callbacks Date: Mon, 26 Jan 2015 15:03:57 +0200 Message-ID: <1589480.9kxdoXKkuz@avalon> References: <1422028288-891-1-git-send-email-m.szyprowski@samsung.com> <2829552.kzfCU5HyxQ@avalon> <20150126110059.GC30345@8bytes.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150126110059.GC30345-zLv9SwRftAIdnm+yROfE0A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Joerg Roedel Cc: Thierry Reding , linux-samsung-soc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Shaik Ameer Basha , Joonyoung Shim , Arnd Bergmann , Rob Herring , Inki Dae , Seung-Woo Kim , Will Deacon , Tomasz Figa , linaro-mm-sig-cunTk1MwBs8s++Sfvej+rw@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Kukjin Kim , Kyungmin Park , Cho KyongHo , David Wodhouse , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: linux-samsung-soc@vger.kernel.org Hi Joerg, On Monday 26 January 2015 12:00:59 Joerg Roedel wrote: > Hi Laurent, > > On Sun, Jan 25, 2015 at 05:38:22PM +0200, Laurent Pinchart wrote: > > IOMMU groups still seem a bit unclear to me. Will Deacon has nicely > > explained what they represent in > > http://lists.infradead.org/pipermail/linux-arm-kernel/2014-December/310816 > > .html. The IOMMU core doesn't make groups > > mandatory, but requires them in some code paths. > > > > For example the coldplug device add function add_iommu_group() called for > > all devices already registered when bus_set_iommu() is called will try to > > warn of devices added multiple times with a WARN_ON(dev->iommu_group). > > Another example is the iommu_bus_notifier() function which will call the > > remove_device() operation only when dev->iommu_group isn't NULL. > > > > I'm thus unsure whether groups should be made mandatory, or whether the > > IOMMU core should be fixed to make them really optional (or, third > > option, whether there's something I haven't understood properly). > > My plan is to make IOMMU groups mandatory. I am currently preparing and > RFC patch-set to introduce default-domains (which will be per group). So > when all IOMMU drivers are converted to make use of default domains the > iommu groups will be mandatory. Could the default domain policy be configured by the IOMMU driver ? The ipmmu- vmsa driver supports four domains only, and serves up to 32 masters, with one group per master. A default of one domain per group wouldn't be usable. -- Regards, Laurent Pinchart From mboxrd@z Thu Jan 1 00:00:00 1970 From: laurent.pinchart@ideasonboard.com (Laurent Pinchart) Date: Mon, 26 Jan 2015 15:03:57 +0200 Subject: [PATCH v5 11/18] iommu: exynos: remove useless device_add/remove callbacks In-Reply-To: <20150126110059.GC30345@8bytes.org> References: <1422028288-891-1-git-send-email-m.szyprowski@samsung.com> <2829552.kzfCU5HyxQ@avalon> <20150126110059.GC30345@8bytes.org> Message-ID: <1589480.9kxdoXKkuz@avalon> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Joerg, On Monday 26 January 2015 12:00:59 Joerg Roedel wrote: > Hi Laurent, > > On Sun, Jan 25, 2015 at 05:38:22PM +0200, Laurent Pinchart wrote: > > IOMMU groups still seem a bit unclear to me. Will Deacon has nicely > > explained what they represent in > > http://lists.infradead.org/pipermail/linux-arm-kernel/2014-December/310816 > > .html. The IOMMU core doesn't make groups > > mandatory, but requires them in some code paths. > > > > For example the coldplug device add function add_iommu_group() called for > > all devices already registered when bus_set_iommu() is called will try to > > warn of devices added multiple times with a WARN_ON(dev->iommu_group). > > Another example is the iommu_bus_notifier() function which will call the > > remove_device() operation only when dev->iommu_group isn't NULL. > > > > I'm thus unsure whether groups should be made mandatory, or whether the > > IOMMU core should be fixed to make them really optional (or, third > > option, whether there's something I haven't understood properly). > > My plan is to make IOMMU groups mandatory. I am currently preparing and > RFC patch-set to introduce default-domains (which will be per group). So > when all IOMMU drivers are converted to make use of default domains the > iommu groups will be mandatory. Could the default domain policy be configured by the IOMMU driver ? The ipmmu- vmsa driver supports four domains only, and serves up to 32 masters, with one group per master. A default of one domain per group wouldn't be usable. -- Regards, Laurent Pinchart