Hello, This patch series fixes the rcar-du-drm driver to support VSP plane sources with an IOMMU. It is available for convenience at git.kernel.org/pub/scm/linux/kernel/git/kbingham/rcar.git vsp-du/iommu-fcp On R-Car Gen3 the DU has no direct memory access but sources planes through VSP instances. When an IOMMU is inserted between the VSP and memory, the DU framebuffers need to be DMA mapped using the VSP device, not the DU device as currently done. The same situation can also be reproduced on Gen2 hardware by linking the VSP to the DU in DT [1], effectively disabling direct memory access by the DU. The situation is made quite complex by the fact that different planes can be connected to different DU instances, and thus served by different IOMMUs (or, in practice on existing hardware, by the same IOMMU but through different micro-TLBs). We thus can't allocate and map buffers to the right device in a single dma_alloc_wc() operation as done in the DRM CMA GEM helpers. However, on such setups, the DU DT node doesn't reference IOMMUs as the DU does not perform any direct memory access. We can thus keep the GEM object allocation unchanged, and the DMA addresses that we receive in the DU driver will be physical addresses. Those buffers then need to be mapped to the VSP device when they are associated with planes. Fortunately the atomic framework provides two plane helper operations, .prepare_fb() and .cleanup_fb() that we can use for this purpose. The reality is slightly more complex than this on Gen3, as an FCP device instance sits between VSP instances and memory. It is the FCP devices that are connected to the IOMMUs, and buffer mapping thus need to be performed using the FCP devices. This isn't required on Gen2 as the platforms don't have any FCPs. Patches 1/5 and 2/5 extend the rcar-fcp driver API to expose the FCP struct device. Patch 3/5 then updates the vsp1 driver to map the display lists and video buffers through the FCP when it exists. This alone fixes VSP operation with an IOMMU on R-Car Gen3 systems. Moving on to addressing the DU issue, patch 4/5 extends the vsp1 driver API to allow mapping a scatter-gather list to the VSP, with the implementation using the FCP devices instead when available. Patch 5/5 finally uses the vsp1 mapping API in the rcar-du-drm driver to map and unmap buffers when needed. The series has been tested on the H2 Lager board and M3-W Salvator-X boards. The IOMMU is known not to work properly on the H3 ES1.1, so the H3 Salvator-X board hasn't been tested. In all cases both the DU and VSP operation has been tested, and tests were run with and without linking the DU and VSP devices to the IOMMU in DT. For H2, the patches were tested on top of v4.12-rc1 with a set of out-of-tree patches to link the VSP and DU to the IOMMUs and to enable VSP+DU combined similar to R-Car Gen3, and an additional DMA mapping API patch [2] that fixes IOMMU operation on ARM32, currently broken in v4.12-rc1. For M3-W, they were were tested on top of renesas-drivers-2017-05-16-v4.12-rc1 with a set of out-of-tree patches to add FCP, VSP, DU and IPMMU instances to the M3-W DT, as well as a hack for the IPMMU driver to whitelist all bus master devices. All tests passed successfully. The issue previously noticed on H3 with synchronization between page flip and VSP operation that was caused by buffers getting unmapped (and possibly freed) before the VSP was done reading them is now gone thanks to the VSP+DU flicker fix that should be merged in v4.13 and is available in renesas-drivers-2017-05-16-v4.12-rc1. A possible improvement is to modify the GEM object allocation mechanism to use non-contiguous memory when the DU driver detects that all the VSP instances it is connected to use an IOMMU (possibly through FCP devices). [1] https://www.mail-archive.com/linux-renesas-soc@xxxxxxxxxxxxxxx/msg06589.html [2] https://www.spinics.net/lists/arm-kernel/msg581410.html Laurent Pinchart (4): v4l: rcar-fcp: Don't get/put module reference v4l: rcar-fcp: Add an API to retrieve the FCP device v4l: vsp1: Add API to map and unmap DRM buffers through the VSP drm: rcar-du: Map memory through the VSP device Magnus Damm (1): v4l: vsp1: Map the DL and video buffers through the proper bus master drivers/gpu/drm/rcar-du/rcar_du_vsp.c | 74 ++++++++++++++++++++++--- drivers/gpu/drm/rcar-du/rcar_du_vsp.h | 2 +- drivers/media/platform/rcar-fcp.c | 17 ++---- drivers/media/platform/vsp1/vsp1.h | 1 +- drivers/media/platform/vsp1/vsp1_dl.c | 4 +- drivers/media/platform/vsp1/vsp1_drm.c | 24 ++++++++- drivers/media/platform/vsp1/vsp1_drv.c | 9 +++- drivers/media/platform/vsp1/vsp1_video.c | 2 +- include/media/rcar-fcp.h | 5 ++- include/media/vsp1.h | 3 +- 10 files changed, 123 insertions(+), 18 deletions(-) base-commit: f2c61f98e0b5f8b53b8fb860e5dcdd661bde7d0b -- git-series 0.9.1
