On Thu, 2012-07-12 at 15:11 +0800, Hiroshi Doyu wrote: > On Thu, 12 Jul 2012 08:49:05 +0200 > markz <markz@xxxxxxxxxx> wrote: > ..... > > > > After Joerg's patch and yours are merged into linux-next, I can submit > > > > my drm patch into review process. > > > > > > You can also send them now for early review with some note mentioning > > > that your patches depend on the above "[PATCH 6/7] iommu/tegra: > > > Implement DOMAIN_ATTR_GEOMETRY attribute" in the commit log. > > > > Thank you. I merged this patch set locally but seems it has problems: > > The requirement of the drm driver is: It needs a parameter named "base" > > while calling function "arm_iommu_create_mapping" to reserve a block of > > iova from GART/SMMU. > > This patch set defines function "iommu_domain_get_attr" & > > "iommu_domain_set_attr", but drm driver can't use them: > > 1. These 2 functions need a iommu_domain param which means the > > iommu_domain should be created before calling them. But the iommu_domain > > is created in function "arm_iommu_create_mapping". > > 2. It's not a good practice to make drm driver calls iommu apis > > directly. > > > > Actually, I'm curious that why function "arm_iommu_create_mapping" needs > > this "base" param. AIUI, drm driver just needs to tell IOMMU the size of > > the iova address to reserve, then the base address can be checked out in > > a lot of ways. For example: > > 1. Via "dma_map_sg" interface -- dma_map_sg defines we can check out the > > mapped iova address from "dma_address" member in scatterlist structure. > > 2. Use this iommu get/set attr interface. Of course, we need some dma > > mapping api wrappers on them. > > arm_iommu_attach_device() should be called independently from DRM > driver in advance. In DRM driver, "struct device" should be connected > to map. Usually this can be done in board files, but with DT, we need > new framework to deal with this at once. Especially in Tegra, we have > many IOMMU'able devices, and it's not good idea to do respectively. > arm_iommu_attach_device() needs "struct dma_iommu_mapping *mapping" which is the return value of arm_iommu_create_mapping(). So we should call arm_iommu_create_mapping in advance. "In DRM driver, "struct device" should be connected to map". What does this "map" means? How "struct device" connects to map? Why we need this? > For temporary solution, you can call arm_iommu_create_mapping() and > arm_iommu_attach_device() in advance before DRM uses DMA API. Yes, this is what I do right now. -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
