On R-Car Gen3, the DU uses a separate IP core named VSP to perform DMA from memory and composition of planes. The DU hardware then only handles the video timings and the interface with the encoders. This differs from Gen2, where the DU included a composer with DMA engines.
When sourcing from the VSP, the DU hardware performs no memory access, and thus has no requirements on imported dma-buf memory types. The GEM CMA helpers however still create a DMA mapping to the DU device, which isn't used. The mapping to the VSP is done when processing the atomic commits, in the plane .prepare_fb() handler.
When the system uses an IOMMU, the VSP device is attached to it, which enables the VSP to use non physically contiguous memory. The DU, as it performs no memory access, isn't connected to the IOMMU. The GEM CMA drm_gem_cma_prime_import_sg_table() helper will in that case fail to map non-contiguous imported dma-bufs, as the DMA mapping to the DU device will have multiple entries in its sgtable. The prevents using non physically contiguous memory for display.
The DRM PRIME and GEM CMA helpers are designed to create the sgtable when the dma-buf is imported. By default, the device referenced by the drm_device is used to create the dma-buf attachment. Drivers can use a different device by using the drm_gem_prime_import_dev() function. While the DU has access to the VSP device, this won't help here, as different CRTCs use different VSP instances, connected to different IOMMU channels. The driver doesn't know at import time which CRTC a GEM object will be used, and thus can't select the right VSP device to pass to drm_gem_prime_import_dev().
To support non-contiguous memory, implement a custom .gem_prime_import_sg_table() operation that accepts all imported dma-buf regardless of the number of scatterlist entries. The sgtable will be mapped to the VSP at .prepare_fb() time, which will reject the framebuffer if the VSP isn't connected to an IOMMU.
Signed-off-by: Laurent Pinchart laurent.pinchart+renesas@ideasonboard.com Reviewed-by: Kieran Bingham kieran.bingham+renesas@ideasonboard.com --- Changes since v2:
- Inline error handling in rcar_du_gem_prime_import_sg_table()
Changes since v1:
- Rewrote commit message to explain issue in more details - Duplicate the imported scatter gather table in rcar_du_vsp_plane_prepare_fb() - Use separate loop counter j to avoid overwritting i - Update to latest drm_gem_cma API --- drivers/gpu/drm/rcar-du/rcar_du_drv.c | 6 +++- drivers/gpu/drm/rcar-du/rcar_du_kms.c | 46 +++++++++++++++++++++++++++ drivers/gpu/drm/rcar-du/rcar_du_kms.h | 7 ++++ drivers/gpu/drm/rcar-du/rcar_du_vsp.c | 36 ++++++++++++++++++--- 4 files changed, 89 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_drv.c b/drivers/gpu/drm/rcar-du/rcar_du_drv.c index 62dfd1b66db0..806c68823a28 100644 --- a/drivers/gpu/drm/rcar-du/rcar_du_drv.c +++ b/drivers/gpu/drm/rcar-du/rcar_du_drv.c @@ -529,7 +529,11 @@ DEFINE_DRM_GEM_CMA_FOPS(rcar_du_fops);
static const struct drm_driver rcar_du_driver = { .driver_features = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC, - DRM_GEM_CMA_DRIVER_OPS_WITH_DUMB_CREATE(rcar_du_dumb_create), + .dumb_create = rcar_du_dumb_create, + .prime_handle_to_fd = drm_gem_prime_handle_to_fd, + .prime_fd_to_handle = drm_gem_prime_fd_to_handle, + .gem_prime_import_sg_table = rcar_du_gem_prime_import_sg_table, + .gem_prime_mmap = drm_gem_prime_mmap, .fops = &rcar_du_fops, .name = "rcar-du", .desc = "Renesas R-Car Display Unit", diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c b/drivers/gpu/drm/rcar-du/rcar_du_kms.c index ca29e4a62816..eacb1f17f747 100644 --- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c +++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c @@ -19,6 +19,7 @@ #include <drm/drm_vblank.h>
#include <linux/device.h> +#include <linux/dma-buf.h> #include <linux/of_graph.h> #include <linux/of_platform.h> #include <linux/wait.h> @@ -325,6 +326,51 @@ const struct rcar_du_format_info *rcar_du_format_info(u32 fourcc) * Frame buffer */
+static const struct drm_gem_object_funcs rcar_du_gem_funcs = { + .free = drm_gem_cma_free_object, + .print_info = drm_gem_cma_print_info, + .get_sg_table = drm_gem_cma_get_sg_table, + .vmap = drm_gem_cma_vmap, + .mmap = drm_gem_cma_mmap, + .vm_ops = &drm_gem_cma_vm_ops, +}; + +struct drm_gem_object *rcar_du_gem_prime_import_sg_table(struct drm_device *dev, + struct dma_buf_attachment *attach, + struct sg_table *sgt) +{ + struct rcar_du_device *rcdu = to_rcar_du_device(dev); + struct drm_gem_cma_object *cma_obj; + struct drm_gem_object *gem_obj; + int ret; + + if (!rcar_du_has(rcdu, RCAR_DU_FEATURE_VSP1_SOURCE)) + return drm_gem_cma_prime_import_sg_table(dev, attach, sgt); + + /* Create a CMA GEM buffer. */ + cma_obj = kzalloc(sizeof(*cma_obj), GFP_KERNEL); + if (!cma_obj) + return ERR_PTR(-ENOMEM); + + gem_obj = &cma_obj->base; + gem_obj->funcs = &rcar_du_gem_funcs; + + drm_gem_private_object_init(dev, gem_obj, attach->dmabuf->size); + cma_obj->map_noncoherent = false; + + ret = drm_gem_create_mmap_offset(gem_obj); + if (ret) { + drm_gem_object_release(gem_obj); + kfree(cma_obj); + return ERR_PTR(ret); + } + + cma_obj->paddr = 0; + cma_obj->sgt = sgt; + + return gem_obj; +} + int rcar_du_dumb_create(struct drm_file *file, struct drm_device *dev, struct drm_mode_create_dumb *args) { diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.h b/drivers/gpu/drm/rcar-du/rcar_du_kms.h index 8f5fff176754..789154e19535 100644 --- a/drivers/gpu/drm/rcar-du/rcar_du_kms.h +++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.h @@ -12,10 +12,13 @@
#include <linux/types.h>
+struct dma_buf_attachment; struct drm_file; struct drm_device; +struct drm_gem_object; struct drm_mode_create_dumb; struct rcar_du_device; +struct sg_table;
struct rcar_du_format_info { u32 fourcc; @@ -34,4 +37,8 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu); int rcar_du_dumb_create(struct drm_file *file, struct drm_device *dev, struct drm_mode_create_dumb *args);
+struct drm_gem_object *rcar_du_gem_prime_import_sg_table(struct drm_device *dev, + struct dma_buf_attachment *attach, + struct sg_table *sgt); + #endif /* __RCAR_DU_KMS_H__ */ diff --git a/drivers/gpu/drm/rcar-du/rcar_du_vsp.c b/drivers/gpu/drm/rcar-du/rcar_du_vsp.c index 23e41c83c875..b7fc5b069cbc 100644 --- a/drivers/gpu/drm/rcar-du/rcar_du_vsp.c +++ b/drivers/gpu/drm/rcar-du/rcar_du_vsp.c @@ -187,17 +187,43 @@ int rcar_du_vsp_map_fb(struct rcar_du_vsp *vsp, struct drm_framebuffer *fb, struct sg_table sg_tables[3]) { struct rcar_du_device *rcdu = vsp->dev; - unsigned int i; + unsigned int i, j; int ret;
for (i = 0; i < fb->format->num_planes; ++i) { struct drm_gem_cma_object *gem = drm_fb_cma_get_gem_obj(fb, i); struct sg_table *sgt = &sg_tables[i];
- ret = dma_get_sgtable(rcdu->dev, sgt, gem->vaddr, gem->paddr, - gem->base.size); - if (ret) - goto fail; + if (gem->sgt) { + struct scatterlist *src; + struct scatterlist *dst; + + /* + * If the GEM buffer has a scatter gather table, it has + * been imported from a dma-buf and has no physical + * address as it might not be physically contiguous. + * Copy the original scatter gather table to map it to + * the VSP. + */ + ret = sg_alloc_table(sgt, gem->sgt->orig_nents, + GFP_KERNEL); + if (ret) + goto fail; + + src = gem->sgt->sgl; + dst = sgt->sgl; + for (j = 0; j < gem->sgt->orig_nents; ++j) { + sg_set_page(dst, sg_page(src), src->length, + src->offset); + src = sg_next(src); + dst = sg_next(dst); + } + } else { + ret = dma_get_sgtable(rcdu->dev, sgt, gem->vaddr, + gem->paddr, gem->base.size); + if (ret) + goto fail; + }
ret = vsp1_du_map_sg(vsp->vsp, sgt); if (ret) {
base-commit: 6880fa6c56601bb8ed59df6c30fd390cc5f6dd8f prerequisite-patch-id: 1955381608912646533b4471b87a245ef305d4b5 prerequisite-patch-id: cfd8a0a525b2ffdb1c3b35a188fb8108c19a5173 prerequisite-patch-id: cbb5d9c7f4e18feea889224d9981fe14ec44097f