From mboxrd@z Thu Jan 1 00:00:00 1970 From: yong.wu@mediatek.com (Yong Wu) Date: Fri, 19 Jun 2015 09:06:12 +0800 Subject: [PATCH v2 2/4] iommu: Implement common IOMMU ops for DMA mapping In-Reply-To: <5582F7C5.8060901@arm.com> References: <1434639625.26953.12.camel@mhfsdcap03> <5582F7C5.8060901@arm.com> Message-ID: <1434675972.30129.0.camel@mhfsdcap03> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, 2015-06-18 at 17:54 +0100, Robin Murphy wrote: > On 18/06/15 16:00, Yong Wu wrote: > > Hi Robin, > > while our drm test, we meet a problem while dma-mmap. > > > > On Thu, 2015-06-11 at 16:54 +0100, Robin Murphy wrote: > >> Taking inspiration from the existing arch/arm code, break out some > >> generic functions to interface the DMA-API to the IOMMU-API. This will > >> do the bulk of the heavy lifting for IOMMU-backed dma-mapping. > >> > >> Signed-off-by: Robin Murphy > >> --- > >> drivers/iommu/Kconfig | 7 + > >> drivers/iommu/Makefile | 1 + > >> drivers/iommu/dma-iommu.c | 560 ++++++++++++++++++++++++++++++++++++++++++++++ > >> include/linux/dma-iommu.h | 94 ++++++++ > >> 4 files changed, 662 insertions(+) > >> create mode 100644 drivers/iommu/dma-iommu.c > >> create mode 100644 include/linux/dma-iommu.h > >> > > [snip] > >> +/** > >> + * iommu_dma_mmap - Map a buffer into provided user VMA > >> + * @pages: Array representing buffer from iommu_dma_alloc() > >> + * @size: Size of buffer in bytes > >> + * @vma: VMA describing requested userspace mapping > >> + * > >> + * Maps the pages of the buffer in @pages into @vma. The caller is responsible > >> + * for verifying the correct size and protection of @vma beforehand. > >> + */ > >> + > >> +int iommu_dma_mmap(struct page **pages, size_t size, struct vm_area_struct *vma) > >> +{ > >> + unsigned long uaddr = vma->vm_start; > >> + unsigned int i, count = PAGE_ALIGN(size) >> PAGE_SHIFT; > >> + int ret = -ENXIO; > >> + > >> + for (i = vma->vm_pgoff; i < count && uaddr < vma->vm_end; i++) { > > Is it : for (i = 0; i < count && uaddr < vma->vm_end; i++) > > According to the patches at [1], respecting vma->pgoff is necessary for > users who only want to mmap part of the buffer. Does your DRM driver by > any chance need the same fix as the Rockchip one? Thanks. We will try to add it. > > >> + ret = vm_insert_page(vma, uaddr, pages[i]); > >> + if (ret) > >> + break; > >> + uaddr += PAGE_SIZE; > >> + } > >> + return ret; > >> +} > >> + > > And to save another email: > > >> + if (WARN_ON(!area || area->pages)) > > Is it: if (WARN_ON(!area || !area->pages)) > >> + return -ENXIO; > > You're absolutely right, thanks. I've got a couple more bugfixes in > progress too, so I'll try to get an updated branch pushed out soon; I'll > hold off posting a v3 to the list until after the upcoming merge window, > though. > > Robin. > > [1]:http://thread.gmane.org/gmane.linux.kernel/1932343 >