From mboxrd@z Thu Jan 1 00:00:00 1970 From: m.szyprowski@samsung.com (Marek Szyprowski) Date: Mon, 24 Oct 2016 08:34:21 +0200 Subject: [PATCH V3 0/8] IOMMU probe deferral support In-Reply-To: <000601d22451$5eb46fc0$1c1d4f40$@codeaurora.org> References: <1475600632-21289-1-git-send-email-sricharan@codeaurora.org> <12cfb59f-f7ca-d4df-eb7f-42348e357979@samsung.com> <000601d22451$5eb46fc0$1c1d4f40$@codeaurora.org> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Sricharan, On 2016-10-12 08:24, Sricharan wrote: > On 2016-10-04 19:03, Sricharan R wrote: >>> Initial post from Laurent Pinchart[1]. This is >>> series calls the dma ops configuration for the devices >>> at a generic place so that it works for all busses. >>> The dma_configure_ops for a device is now called during >>> the device_attach callback just before the probe of the >>> bus/driver is called. Similarly dma_deconfigure is called during >>> device/driver_detach path. >>> >>> >>> pci_bus_add_devices (platform/amba)(_device_create/driver_register) >>> | | >>> pci_bus_add_device (device_add/driver_register) >>> | | >>> device_attach device_initial_probe >>> | | >>> __device_attach_driver __device_attach_driver >>> | >>> driver_probe_device >>> | >>> really_probe >>> | >>> dma_configure >>> >>> Similarly on the device/driver_unregister path __device_release_driver is >>> called which inturn calls dma_deconfigure. >>> >>> If the ACPI bus code follows the same, we can add acpi_dma_configure >>> at the same place as of_dma_configure. >>> >>> This series is based on the recently merged Generic DT bindings for >>> PCI IOMMUs and ARM SMMU from Robin Murphy robin.murphy at arm.com [2] >>> >>> This time tested this with platform and pci device for probe deferral >>> and reprobe on arm64 based platform. There is an issue on the cleanup >>> path for arm64 though, where there is WARN_ON if the dma_ops is reset while >>> device is attached to an domain in arch_teardown_dma_ops. >>> But with iommu_groups created from the iommu driver, the device is always >>> attached to a domain/default_domain. So so the WARN has to be removed/handled >>> probably. >> Thanks for continuing work on this feature! Your can add my: >> >> Tested-by: Marek Szyprowski >> > Thanks for testing this. So the for the below fix, the remove_device callback > gets called on the dma_ops cleanup path, so would it be easy to remove the > data for the device there ? I assumed that IOMMU driver cannot be removed reliably, so all structures that it creates are permanent. I didn't use device_add()/device_remove() callbacks, because in current implementation device_add() is called too late (after dma-mapping glue triggers device_attach_iommu()). Maybe once your patchset is merged, I will move creation and management of the all IOMMU related structures to device_add/remove callbacks. Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland