On Wednesday 11 April 2012, Thierry Reding wrote: > * Daniel Vetter wrote: > > On Wed, Apr 11, 2012 at 03:23:26PM +0200, Thierry Reding wrote: > > > * Daniel Vetter wrote: > > > > On Wed, Apr 11, 2012 at 02:10:30PM +0200, Thierry Reding wrote: > > > > > This commit adds a very basic DRM driver for NVIDIA Tegra SoCs. It > > > > > currently has rudimentary GEM support and can run a console on the > > > > > framebuffer as well as X using the xf86-video-modesetting driver. > > > > > Only the RGB output is supported. Quite a lot of things still need > > > > > to be worked out and there is a lot of room for cleanup. > > > > > > > > Indeed, after a quick look there are tons of functions that are just stubs > > > > ;-) One thing I wonder though is why you directly use the iommu api and > > > > not wrap it up into dma_map? Is arm infrastructure just not there yet or > > > > do you plan to tightly integrate the tegra drm with the iommu (e.g. for > > > > process space switching or similarly funky stuff)? > > > > > > I'm not sure I know what you are referring to. Looking for all users of > > > iommu_map() doesn't turn up anything related to dma_map. Can you point me in > > > the right direction? > > > > Well, you use the iommu api to map/unmap memory into the iommu for tegra, > > whereas usually device drivers just use the dma api to do that. The usual > > interface is dma_map_sg/dma_unmap_sg, but there are quite a few variants > > around. I'm just wondering why this you've choosen this. > > I don't think this works on ARM. Maybe I'm not seeing the whole picture but > judging by a quick look through the kernel tree there aren't any users that > map DMA memory through an IOMMU. dma_map_sg is certainly the right interface to use, and Marek Szyprowski has patches to make that work on ARM, hopefully going into v3.5, so you could use those. Arnd -- 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
