Hi Liviu,
Thank you for the patch.
On Friday, 10 November 2017 15:33:10 EET Liviu Dudau wrote:
> drm_gem_cma_prime_import_sg_table() will fail if the number of entries
> in the sg_table > 1. However, you can have a device that uses an IOMMU
> engine and can map a discontiguous buffer with multiple entries that
> have consecutive sg_dma_addresses, effectively making it contiguous.
> Allow for that scenario by testing the entries in the sg_table for
> contiguous coverage.
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> Signed-off-by: Liviu Dudau <liviu.dudau@xxxxxxx>
> ---
>
> Laurent,
>
> Thanks for the review! I would like to ask for one more favour: if you
> are OK with this version, can you pull this patch through the drm-misc tree?
I could, but I'd first need to set dim up, and I'm currently abroad with a bad
internet connection and a big deadline for the middle of next week (I know,
lots of excuses), so it's not very convenient for me at this time.
> drivers/gpu/drm/drm_gem_cma_helper.c | 22 ++++++++++++++++++++--
> include/drm/drm_gem_cma_helper.h | 4 +++-
> 2 files changed, 23 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c
> b/drivers/gpu/drm/drm_gem_cma_helper.c index 020e7668dfaba..43b179212052d
> 100644
> --- a/drivers/gpu/drm/drm_gem_cma_helper.c
> +++ b/drivers/gpu/drm/drm_gem_cma_helper.c
> @@ -482,8 +482,26 @@ drm_gem_cma_prime_import_sg_table(struct drm_device
> *dev, {
> struct drm_gem_cma_object *cma_obj;
>
> - if (sgt->nents != 1)
> - return ERR_PTR(-EINVAL);
> + if (sgt->nents != 1) {
> + /* check if the entries in the sg_table are contiguous */
> + dma_addr_t next_addr = sg_dma_address(sgt->sgl);
> + struct scatterlist *s;
> + unsigned int i;
> +
> + for_each_sg(sgt->sgl, s, sgt->nents, i) {
> + /*
> + * sg_dma_address(s) is only valid for entries
> + * that have sg_dma_len(s) != 0
> + */
> + if (!sg_dma_len(s))
> + continue;
> +
> + if (sg_dma_address(s) != next_addr)
> + return ERR_PTR(-EINVAL);
> +
> + next_addr = sg_dma_address(s) + sg_dma_len(s);
> + }
> + }
>
> /* Create a CMA GEM buffer. */
> cma_obj = __drm_gem_cma_create(dev, attach->dmabuf->size);
> diff --git a/include/drm/drm_gem_cma_helper.h
> b/include/drm/drm_gem_cma_helper.h index 58a739bf15f1f..214aa85adc8d5
> 100644
> --- a/include/drm/drm_gem_cma_helper.h
> +++ b/include/drm/drm_gem_cma_helper.h
> @@ -8,7 +8,9 @@
> * struct drm_gem_cma_object - GEM object backed by CMA memory allocations
> * @base: base GEM object
> * @paddr: physical address of the backing memory
> - * @sgt: scatter/gather table for imported PRIME buffers
> + * @sgt: scatter/gather table for imported PRIME buffers. The table can
> have + * more than one entry but they are guaranteed to have
> contiguous + * DMA addresses.
> * @vaddr: kernel virtual address of the backing memory
> */
> struct drm_gem_cma_object {
--
Regards,
Laurent Pinchart
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