Hi all,
On Wed, 27 Oct 2021 15:37:39 +1100 Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote:
>
> Today's linux-next merge of the char-misc tree got a conflict in:
>
> drivers/gpu/drm/tegra/gem.c
>
> between commit:
>
> 1c4d17a5267b ("drm/tegra: Implement correct DMA-BUF semantics")
>
> from the drm-tegra tree and commit:
>
> 16b0314aa746 ("dma-buf: move dma-buf symbols into the DMA_BUF module namespace")
>
> from the char-misc tree.
>
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging. You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.
>
> --
> Cheers,
> Stephen Rothwell
>
> diff --cc drivers/gpu/drm/tegra/gem.c
> index 62fc7e8429d4,d38fd7e12b57..000000000000
> --- a/drivers/gpu/drm/tegra/gem.c
> +++ b/drivers/gpu/drm/tegra/gem.c
> @@@ -20,78 -21,60 +21,80 @@@
> #include "drm.h"
> #include "gem.h"
>
> + MODULE_IMPORT_NS(DMA_BUF);
> +
> -static void tegra_bo_put(struct host1x_bo *bo)
> +static unsigned int sg_dma_count_chunks(struct scatterlist *sgl, unsigned int nents)
> {
> - struct tegra_bo *obj = host1x_to_tegra_bo(bo);
> + dma_addr_t next = ~(dma_addr_t)0;
> + unsigned int count = 0, i;
> + struct scatterlist *s;
> +
> + for_each_sg(sgl, s, 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) {
> + next = sg_dma_address(s) + sg_dma_len(s);
> + count++;
> + }
> + }
>
> - drm_gem_object_put(&obj->gem);
> + return count;
> }
>
> -/* XXX move this into lib/scatterlist.c? */
> -static int sg_alloc_table_from_sg(struct sg_table *sgt, struct scatterlist *sg,
> - unsigned int nents, gfp_t gfp_mask)
> +static inline unsigned int sgt_dma_count_chunks(struct sg_table *sgt)
> {
> - struct scatterlist *dst;
> - unsigned int i;
> - int err;
> -
> - err = sg_alloc_table(sgt, nents, gfp_mask);
> - if (err < 0)
> - return err;
> -
> - dst = sgt->sgl;
> + return sg_dma_count_chunks(sgt->sgl, sgt->nents);
> +}
>
> - for (i = 0; i < nents; i++) {
> - sg_set_page(dst, sg_page(sg), sg->length, 0);
> - dst = sg_next(dst);
> - sg = sg_next(sg);
> - }
> +static void tegra_bo_put(struct host1x_bo *bo)
> +{
> + struct tegra_bo *obj = host1x_to_tegra_bo(bo);
>
> - return 0;
> + drm_gem_object_put(&obj->gem);
> }
>
> -static struct sg_table *tegra_bo_pin(struct device *dev, struct host1x_bo *bo,
> - dma_addr_t *phys)
> +static struct host1x_bo_mapping *tegra_bo_pin(struct device *dev, struct host1x_bo *bo,
> + enum dma_data_direction direction)
> {
> struct tegra_bo *obj = host1x_to_tegra_bo(bo);
> - struct sg_table *sgt;
> + struct drm_gem_object *gem = &obj->gem;
> + struct host1x_bo_mapping *map;
> int err;
>
> + map = kzalloc(sizeof(*map), GFP_KERNEL);
> + if (!map)
> + return ERR_PTR(-ENOMEM);
> +
> + kref_init(&map->ref);
> + map->bo = host1x_bo_get(bo);
> + map->direction = direction;
> + map->dev = dev;
> +
> /*
> - * If we've manually mapped the buffer object through the IOMMU, make
> - * sure to return the IOVA address of our mapping.
> - *
> - * Similarly, for buffers that have been allocated by the DMA API the
> - * physical address can be used for devices that are not attached to
> - * an IOMMU. For these devices, callers must pass a valid pointer via
> - * the @phys argument.
> - *
> - * Imported buffers were also already mapped at import time, so the
> - * existing mapping can be reused.
> + * Imported buffers need special treatment to satisfy the semantics of DMA-BUF.
> */
> - if (phys) {
> - *phys = obj->iova;
> - return NULL;
> + if (gem->import_attach) {
> + struct dma_buf *buf = gem->import_attach->dmabuf;
> +
> + map->attach = dma_buf_attach(buf, dev);
> + if (IS_ERR(map->attach)) {
> + err = PTR_ERR(map->attach);
> + goto free;
> + }
> +
> + map->sgt = dma_buf_map_attachment(map->attach, direction);
> + if (IS_ERR(map->sgt)) {
> + dma_buf_detach(buf, map->attach);
> + err = PTR_ERR(map->sgt);
> + goto free;
> + }
> +
> + err = sgt_dma_count_chunks(map->sgt);
> + map->size = gem->size;
> +
> + goto out;
> }
>
> /*
This is now a conflict between the drm-tegra tree and Linus' tree.
--
Cheers,
Stephen Rothwell
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