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SubjectRe: [PATCH] drm: omapdrm: Improve check for contiguous buffers
From
On 8/22/22 7:03 PM, Andrew Davis wrote:
> While a scatter-gather table having only 1 entry does imply it is
> contiguous, it is a logic error to assume the inverse. Tables can have
> more than 1 entry and still be contiguous. Use a proper check here.
>
> Signed-off-by: Andrew Davis <afd@ti.com>
> ---


Looks like an old version of this patch got in my to-send queue,
please ignore this one, will send updated v2.

Thanks,
Andrew


> drivers/gpu/drm/omapdrm/omap_gem.c | 14 ++++++++++----
> 1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
> index cf571796fd26..52c00b795459 100644
> --- a/drivers/gpu/drm/omapdrm/omap_gem.c
> +++ b/drivers/gpu/drm/omapdrm/omap_gem.c
> @@ -48,7 +48,7 @@ struct omap_gem_object {
> * OMAP_BO_MEM_DMA_API flag set)
> *
> * - buffers imported from dmabuf (with the OMAP_BO_MEM_DMABUF flag set)
> - * if they are physically contiguous (when sgt->orig_nents == 1)
> + * if they are physically contiguous
> *
> * - buffers mapped through the TILER when pin_cnt is not zero, in which
> * case the DMA address points to the TILER aperture
> @@ -148,12 +148,18 @@ u64 omap_gem_mmap_offset(struct drm_gem_object *obj)
> return drm_vma_node_offset_addr(&obj->vma_node);
> }
>
> +static bool omap_gem_sgt_is_contiguous(struct sg_table *sgt, size)
> +{
> + return !(drm_prime_get_contiguous_size(sgt) < size);
> +}
> +
> static bool omap_gem_is_contiguous(struct omap_gem_object *omap_obj)
> {
> if (omap_obj->flags & OMAP_BO_MEM_DMA_API)
> return true;
>
> - if ((omap_obj->flags & OMAP_BO_MEM_DMABUF) && omap_obj->sgt->nents == 1)
> + if ((omap_obj->flags & OMAP_BO_MEM_DMABUF) &&
> + omap_gem_sgt_is_contiguous(omap_obj->sgt, omap_obj->base->size))
> return true;
>
> return false;
> @@ -1398,7 +1404,7 @@ struct drm_gem_object *omap_gem_new_dmabuf(struct drm_device *dev, size_t size,
> union omap_gem_size gsize;
>
> /* Without a DMM only physically contiguous buffers can be supported. */
> - if (sgt->orig_nents != 1 && !priv->has_dmm)
> + if (!omap_gem_sgt_is_contiguous(sgt, size) && !priv->has_dmm)
> return ERR_PTR(-EINVAL);
>
> gsize.bytes = PAGE_ALIGN(size);
> @@ -1412,7 +1418,7 @@ struct drm_gem_object *omap_gem_new_dmabuf(struct drm_device *dev, size_t size,
>
> omap_obj->sgt = sgt;
>
> - if (sgt->orig_nents == 1) {
> + if (omap_gem_sgt_is_contiguous(sgt, size)) {
> omap_obj->dma_addr = sg_dma_address(sgt->sgl);
> } else {
> /* Create pages list from sgt */

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