From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH 1/2] iommu: call detach also for default_domain before attaching to new one Date: Wed, 17 Feb 2016 12:14:50 +0100 Message-ID: <20160217111450.GA18805@8bytes.org> References: <1455633632-16873-1-git-send-email-m.szyprowski@samsung.com> <1455633632-16873-2-git-send-email-m.szyprowski@samsung.com> <20160216155922.GV18805@8bytes.org> <56C422AE.9000108@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <56C422AE.9000108-Sze3O3UU22JBDgjK7y7TUQ@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: Marek Szyprowski Cc: linaro-mm-sig-cunTk1MwBs8s++Sfvej+rw@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Bartlomiej Zolnierkiewicz List-Id: iommu@lists.linux-foundation.org On Wed, Feb 17, 2016 at 08:35:10AM +0100, Marek Szyprowski wrote: > Huh, I wasn't aware of this change in the iommu drivers api. For some > drivers attach/detach callbacks does something more than just programming > page table base register, like for example in case of exynos iommu it is > enabling runtime power management and clocks. The code is really > much simpler > if those calls are balanced, but if the goal is to allow multiple > unballanced > attach calls, I will try to fix this in our driver. > > Maybe it should be documented somewhere, that attach calls can be > unbalanced? Well, when your driver uses default-domains, the detach_dev call-back is not used anymore. The attach_dev call-back is supposed to just overwrite any existing binding that may exist for the device. So the calls are not unbalanced, the detach_dev calls just don't happen anymore. Joerg