Hi Christoph I have started now to give a try to your patchset. Sorry for the delay. For uvc I have prepared this patch: https://github.com/ribalda/linux/commit/9094fe223fe38f8c8ff21366d893b43cbbdf0113 I have tested successfully in a x86_64 noteboot..., yes I know there is no change for that platform :). I am trying to get hold of an arm device that can run the latest kernel from upstream. On the meanwhile if you could take a look to the patch to verify that this the way that you expect the drivers to use your api I would appreciate it Thanks On Wed, Oct 14, 2020 at 3:20 PM Tomasz Figa <tfiga@xxxxxxxxxxxx> wrote: > > +CC Ricardo who will be looking into using this in the USB stack (UVC > camera driver). > > On Wed, Sep 30, 2020 at 6:09 PM Christoph Hellwig <hch@xxxxxx> wrote: > > > > Add a new API that returns a virtually non-contigous array of pages > > and dma address. This API is only implemented for dma-iommu and will > > not be implemented for non-iommu DMA API instances that have to allocate > > contiguous memory. It is up to the caller to check if the API is > > available. > > > > The intent is that media drivers can use this API if either: > > > > - no kernel mapping or only temporary kernel mappings are required. > > That is as a better replacement for DMA_ATTR_NO_KERNEL_MAPPING > > - a kernel mapping is required for cached and DMA mapped pages, but > > the driver also needs the pages to e.g. map them to userspace. > > In that sense it is a replacement for some aspects of the recently > > removed and never fully implemented DMA_ATTR_NON_CONSISTENT > > > > Signed-off-by: Christoph Hellwig <hch@xxxxxx> > > --- > > drivers/iommu/dma-iommu.c | 73 +++++++++++++++++++++++++------------ > > include/linux/dma-mapping.h | 9 +++++ > > kernel/dma/mapping.c | 35 ++++++++++++++++++ > > 3 files changed, 93 insertions(+), 24 deletions(-) > > > > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c > > index 7922f545cd5eef..158026a856622c 100644 > > --- a/drivers/iommu/dma-iommu.c > > +++ b/drivers/iommu/dma-iommu.c > > @@ -565,23 +565,12 @@ static struct page **__iommu_dma_alloc_pages(struct device *dev, > > return pages; > > } > > > > -/** > > - * iommu_dma_alloc_remap - Allocate and map a buffer contiguous in IOVA space > > - * @dev: Device to allocate memory for. Must be a real device > > - * attached to an iommu_dma_domain > > - * @size: Size of buffer in bytes > > - * @dma_handle: Out argument for allocated DMA handle > > - * @gfp: Allocation flags > > - * @prot: pgprot_t to use for the remapped mapping > > - * @attrs: DMA attributes for this allocation > > - * > > - * If @size is less than PAGE_SIZE, then a full CPU page will be allocated, > > +/* > > + * If size is less than PAGE_SIZE, then a full CPU page will be allocated, > > * but an IOMMU which supports smaller pages might not map the whole thing. > > - * > > - * Return: Mapped virtual address, or NULL on failure. > > */ > > -static void *iommu_dma_alloc_remap(struct device *dev, size_t size, > > - dma_addr_t *dma_handle, gfp_t gfp, pgprot_t prot, > > +static struct page **__iommu_dma_alloc_noncontiguous(struct device *dev, > > + size_t size, dma_addr_t *dma_handle, gfp_t gfp, pgprot_t prot, > > unsigned long attrs) > > { > > struct iommu_domain *domain = iommu_get_dma_domain(dev); > > @@ -593,7 +582,6 @@ static void *iommu_dma_alloc_remap(struct device *dev, size_t size, > > struct page **pages; > > struct sg_table sgt; > > dma_addr_t iova; > > - void *vaddr; > > > > *dma_handle = DMA_MAPPING_ERROR; > > > > @@ -636,17 +624,10 @@ static void *iommu_dma_alloc_remap(struct device *dev, size_t size, > > < size) > > goto out_free_sg; > > > > - vaddr = dma_common_pages_remap(pages, size, prot, > > - __builtin_return_address(0)); > > - if (!vaddr) > > - goto out_unmap; > > - > > *dma_handle = iova; > > sg_free_table(&sgt); > > - return vaddr; > > + return pages; > > > > -out_unmap: > > - __iommu_dma_unmap(dev, iova, size); > > out_free_sg: > > sg_free_table(&sgt); > > out_free_iova: > > @@ -656,6 +637,46 @@ static void *iommu_dma_alloc_remap(struct device *dev, size_t size, > > return NULL; > > } > > > > +static void *iommu_dma_alloc_remap(struct device *dev, size_t size, > > + dma_addr_t *dma_handle, gfp_t gfp, pgprot_t prot, > > + unsigned long attrs) > > +{ > > + struct page **pages; > > + void *vaddr; > > + > > + pages = __iommu_dma_alloc_noncontiguous(dev, size, dma_handle, gfp, > > + prot, attrs); > > + if (!pages) > > + return NULL; > > + vaddr = dma_common_pages_remap(pages, size, prot, > > + __builtin_return_address(0)); > > + if (!vaddr) > > + goto out_unmap; > > + return vaddr; > > + > > +out_unmap: > > + __iommu_dma_unmap(dev, *dma_handle, size); > > + __iommu_dma_free_pages(pages, PAGE_ALIGN(size) >> PAGE_SHIFT); > > + return NULL; > > +} > > + > > +#ifdef CONFIG_DMA_REMAP > > +static struct page **iommu_dma_alloc_noncontiguous(struct device *dev, > > + size_t size, dma_addr_t *dma_handle, gfp_t gfp, > > + unsigned long attrs) > > +{ > > + return __iommu_dma_alloc_noncontiguous(dev, size, dma_handle, gfp, > > + PAGE_KERNEL, attrs); > > +} > > + > > +static void iommu_dma_free_noncontiguous(struct device *dev, size_t size, > > + struct page **pages, dma_addr_t dma_handle) > > +{ > > + __iommu_dma_unmap(dev, dma_handle, size); > > + __iommu_dma_free_pages(pages, PAGE_ALIGN(size) >> PAGE_SHIFT); > > +} > > +#endif > > + > > static void iommu_dma_sync_single_for_cpu(struct device *dev, > > dma_addr_t dma_handle, size_t size, enum dma_data_direction dir) > > { > > @@ -1110,6 +1131,10 @@ static const struct dma_map_ops iommu_dma_ops = { > > .free = iommu_dma_free, > > .alloc_pages = dma_common_alloc_pages, > > .free_pages = dma_common_free_pages, > > +#ifdef CONFIG_DMA_REMAP > > + .alloc_noncontiguous = iommu_dma_alloc_noncontiguous, > > + .free_noncontiguous = iommu_dma_free_noncontiguous, > > +#endif > > .mmap = iommu_dma_mmap, > > .get_sgtable = iommu_dma_get_sgtable, > > .map_page = iommu_dma_map_page, > > diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h > > index 4b9b1d64f5ec9e..51bbc32365bb8d 100644 > > --- a/include/linux/dma-mapping.h > > +++ b/include/linux/dma-mapping.h > > @@ -74,6 +74,10 @@ struct dma_map_ops { > > gfp_t gfp); > > void (*free_pages)(struct device *dev, size_t size, struct page *vaddr, > > dma_addr_t dma_handle, enum dma_data_direction dir); > > + struct page **(*alloc_noncontiguous)(struct device *dev, size_t size, > > + dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs); > > + void (*free_noncontiguous)(struct device *dev, size_t size, > > + struct page **pages, dma_addr_t dma_handle); > > int (*mmap)(struct device *, struct vm_area_struct *, > > void *, dma_addr_t, size_t, > > unsigned long attrs); > > @@ -384,6 +388,11 @@ void *dma_alloc_noncoherent(struct device *dev, size_t size, > > dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp); > > void dma_free_noncoherent(struct device *dev, size_t size, void *vaddr, > > dma_addr_t dma_handle, enum dma_data_direction dir); > > +bool dma_can_alloc_noncontiguous(struct device *dev); > > +struct page **dma_alloc_noncontiguous(struct device *dev, size_t size, > > + dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs); > > +void dma_free_noncontiguous(struct device *dev, size_t size, > > + struct page **pages, dma_addr_t dma_handle); > > > > static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr, > > size_t size, enum dma_data_direction dir, unsigned long attrs) > > diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c > > index 06115f59f4ffbf..6d975d1a20dd72 100644 > > --- a/kernel/dma/mapping.c > > +++ b/kernel/dma/mapping.c > > @@ -529,6 +529,41 @@ void dma_free_noncoherent(struct device *dev, size_t size, void *vaddr, > > } > > EXPORT_SYMBOL_GPL(dma_free_noncoherent); > > > > +bool dma_can_alloc_noncontiguous(struct device *dev) > > +{ > > + const struct dma_map_ops *ops = get_dma_ops(dev); > > + > > + return ops && ops->free_noncontiguous; > > +} > > +EXPORT_SYMBOL_GPL(dma_can_alloc_noncontiguous); > > + > > +struct page **dma_alloc_noncontiguous(struct device *dev, size_t size, > > + dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs) > > +{ > > + const struct dma_map_ops *ops = get_dma_ops(dev); > > + > > + if (WARN_ON_ONCE(!dma_can_alloc_noncontiguous(dev))) > > + return NULL; > > + if (attrs & ~DMA_ATTR_ALLOC_SINGLE_PAGES) { > > + dev_warn(dev, "invalid flags (0x%lx) for %s\n", > > + attrs, __func__); > > + return NULL; > > + } > > + return ops->alloc_noncontiguous(dev, size, dma_handle, gfp, attrs); > > +} > > +EXPORT_SYMBOL_GPL(dma_alloc_noncontiguous); > > + > > +void dma_free_noncontiguous(struct device *dev, size_t size, > > + struct page **pages, dma_addr_t dma_handle) > > +{ > > + const struct dma_map_ops *ops = get_dma_ops(dev); > > + > > + if (WARN_ON_ONCE(!dma_can_alloc_noncontiguous(dev))) > > + return; > > + ops->free_noncontiguous(dev, size, pages, dma_handle); > > +} > > +EXPORT_SYMBOL_GPL(dma_free_noncontiguous); > > + > > int dma_supported(struct device *dev, u64 mask) > > { > > const struct dma_map_ops *ops = get_dma_ops(dev); > > -- > > 2.28.0 > > -- Ricardo Ribalda
