From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH v6 1/8] iommu: provide early initialisation hook for IOMMU drivers Date: Thu, 04 Dec 2014 12:19:32 +0100 Message-ID: <5643715.BADzWxcqOQ@wuerfel> References: <1417453034-21379-1-git-send-email-will.deacon@arm.com> <3152553.esaQuZiCgi@wuerfel> <20141204102127.GF13224@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20141204102127.GF13224-5wv7dgnIgG8@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: Will Deacon Cc: "jroedel-l3A5Bk7waGM@public.gmane.org" , Pantelis Antoniou , Linux IOMMU , Thierry Reding , Rob Herring , Laurent Pinchart , "grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" , Varun Sethi , David Woodhouse , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: iommu@lists.linux-foundation.org On Thursday 04 December 2014 10:21:27 Will Deacon wrote: > On Thu, Dec 04, 2014 at 10:10:17AM +0000, Arnd Bergmann wrote: > > On Thursday 04 December 2014 09:49:53 Will Deacon wrote: > > > On Wed, Dec 03, 2014 at 07:57:50PM +0000, Arnd Bergmann wrote: > > > > On Tuesday 02 December 2014 14:16:57 Grant Likely wrote: > > > > > On Mon, Dec 1, 2014 at 11:54 PM, Rob Herring wrote: > > > > > > On Mon, Dec 1, 2014 at 10:57 AM, Will Deacon wrote: > > > > > >> > > > > > >> +static inline void of_iommu_set_ops(struct device_node *np, > > > > > >> + const struct iommu_ops *ops) > > > > > >> +{ > > > > > >> + np->data = (struct iommu_ops *)ops; > > > > > >> +} > > > > > >> + > > > > > >> +static inline struct iommu_ops *of_iommu_get_ops(struct device_node *np) > > > > > >> +{ > > > > > >> + return np->data; > > > > > >> +} > > > > > > > > > > > > This may collide with other users. While use of it is rare, PPC uses > > > > > > it in its PCI code. The OF_DYNAMIC code frees it but never actually > > > > > > sets it. There may be some coming usage with the DT overlay code or > > > > > > that's just a bug. Pantelis or Grant can comment. If not, I think we > > > > > > really should try to get rid of this pointer rather than expand it's > > > > > > usage. > > > > > > > > > > > > I didn't see a user of this. I'm guessing that is coming in a SMMU patch? > > > > > > > > > > Good catch. This is not good. The data pointer should be avoided since > > > > > there are no controls over its use. Until a better solution can be > > > > > implemented, probably the safest thing to do is add a struct iommu_ops > > > > > pointer to struct device_node. However, assuming that only a small > > > > > portion of nodes will actually have iommu_ops set, I'd rather see a > > > > > separate registry that matches device_nodes to iommu_ops. > > > > > > > > Fair enough. Will, can you take a copy of drivers/dma/of-dma.c and > > > > adapt it as needed? It should be exactly what we need to start > > > > out and can be extended and generalized later. > > > > > > Sure, I'll add this to my list of stuff to do for 3.20. > > > > Does that mean the we don't get any of the patches for 3.19 despite the > > Acks? > > Hmm, I don't know how useful they are without the get/set ops and I don't > think I can get those ready for 3.19 given where we currently are. > > Grant's suggestion of adding an iommu_ops pointer to device_node would work > as a temporary hack, but anything more advanced is going to need proper > review. Right. I guess it doesn't hurt much if we put the new pointer inside #ifdef CONFIG_OF_IOMMU, then at least there is no significant size increase in most DT based platforms. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Thu, 04 Dec 2014 12:19:32 +0100 Subject: [PATCH v6 1/8] iommu: provide early initialisation hook for IOMMU drivers In-Reply-To: <20141204102127.GF13224@arm.com> References: <1417453034-21379-1-git-send-email-will.deacon@arm.com> <3152553.esaQuZiCgi@wuerfel> <20141204102127.GF13224@arm.com> Message-ID: <5643715.BADzWxcqOQ@wuerfel> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thursday 04 December 2014 10:21:27 Will Deacon wrote: > On Thu, Dec 04, 2014 at 10:10:17AM +0000, Arnd Bergmann wrote: > > On Thursday 04 December 2014 09:49:53 Will Deacon wrote: > > > On Wed, Dec 03, 2014 at 07:57:50PM +0000, Arnd Bergmann wrote: > > > > On Tuesday 02 December 2014 14:16:57 Grant Likely wrote: > > > > > On Mon, Dec 1, 2014 at 11:54 PM, Rob Herring wrote: > > > > > > On Mon, Dec 1, 2014 at 10:57 AM, Will Deacon wrote: > > > > > >> > > > > > >> +static inline void of_iommu_set_ops(struct device_node *np, > > > > > >> + const struct iommu_ops *ops) > > > > > >> +{ > > > > > >> + np->data = (struct iommu_ops *)ops; > > > > > >> +} > > > > > >> + > > > > > >> +static inline struct iommu_ops *of_iommu_get_ops(struct device_node *np) > > > > > >> +{ > > > > > >> + return np->data; > > > > > >> +} > > > > > > > > > > > > This may collide with other users. While use of it is rare, PPC uses > > > > > > it in its PCI code. The OF_DYNAMIC code frees it but never actually > > > > > > sets it. There may be some coming usage with the DT overlay code or > > > > > > that's just a bug. Pantelis or Grant can comment. If not, I think we > > > > > > really should try to get rid of this pointer rather than expand it's > > > > > > usage. > > > > > > > > > > > > I didn't see a user of this. I'm guessing that is coming in a SMMU patch? > > > > > > > > > > Good catch. This is not good. The data pointer should be avoided since > > > > > there are no controls over its use. Until a better solution can be > > > > > implemented, probably the safest thing to do is add a struct iommu_ops > > > > > pointer to struct device_node. However, assuming that only a small > > > > > portion of nodes will actually have iommu_ops set, I'd rather see a > > > > > separate registry that matches device_nodes to iommu_ops. > > > > > > > > Fair enough. Will, can you take a copy of drivers/dma/of-dma.c and > > > > adapt it as needed? It should be exactly what we need to start > > > > out and can be extended and generalized later. > > > > > > Sure, I'll add this to my list of stuff to do for 3.20. > > > > Does that mean the we don't get any of the patches for 3.19 despite the > > Acks? > > Hmm, I don't know how useful they are without the get/set ops and I don't > think I can get those ready for 3.19 given where we currently are. > > Grant's suggestion of adding an iommu_ops pointer to device_node would work > as a temporary hack, but anything more advanced is going to need proper > review. Right. I guess it doesn't hurt much if we put the new pointer inside #ifdef CONFIG_OF_IOMMU, then at least there is no significant size increase in most DT based platforms. Arnd