Re: [PATCH v2 14/22] media: rockchip: rga: support external iommus

From: Nicolas Dufresne
Date: Wed Dec 24 2025 - 10:50:27 EST

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Le mercredi 03 décembre 2025 à 16:52 +0100, Sven Püschel a écrit :
> In preparation for the RGA3 add support for external iommus. This is a
> transition step to just disable the RGA2 specific mmu table setup code.
>
> Currently a simple rga_hw struct field is used to set the internal iommu.
> But to handle the case of more sophisticated detection mechanisms
> (e.g. check for an iommu property in the device tree), it is abstracted
> by an inline function.
>
> Signed-off-by: Sven Püschel <s.pueschel@xxxxxxxxxxxxxx>
> ---
> drivers/media/platform/rockchip/rga/rga-buf.c | 46 ++++++++++++++++-----------
> drivers/media/platform/rockchip/rga/rga-hw.c | 1 +
> drivers/media/platform/rockchip/rga/rga.c     | 11 +++++--
> drivers/media/platform/rockchip/rga/rga.h     | 6 ++++
> 4 files changed, 43 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/media/platform/rockchip/rga/rga-buf.c b/drivers/media/platform/rockchip/rga/rga-buf.c
> index 8845e1f894f29..e8d1e2e579140 100644
> --- a/drivers/media/platform/rockchip/rga/rga-buf.c
> +++ b/drivers/media/platform/rockchip/rga/rga-buf.c
> @@ -12,6 +12,7 @@
> #include <media/v4l2-ioctl.h>
> #include <media/v4l2-mem2mem.h>
> #include <media/videobuf2-dma-sg.h>
> +#include <media/videobuf2-dma-contig.h>
> #include <media/videobuf2-v4l2.h>
>
> #include "rga.h"
> @@ -79,14 +80,16 @@ static int rga_buf_init(struct vb2_buffer *vb)
> struct rga_frame *f = rga_get_frame(ctx, vb->vb2_queue->type);
> size_t n_desc = 0;
>
> - n_desc = DIV_ROUND_UP(f->size, PAGE_SIZE);
> + if (rga_has_internal_iommu(rga)) {
> + n_desc = DIV_ROUND_UP(f->size, PAGE_SIZE);

n_desc is not used outside of this scope, perhap drop the definition with the 0
init, and use:

const size_t n_desc = DIV_ROUND_UP(f->size, PAGE_SIZE);

>
> - rbuf->n_desc = n_desc;
> - rbuf->dma_desc = dma_alloc_coherent(rga->dev,
> -     rbuf->n_desc * sizeof(*rbuf->dma_desc),
> -     &rbuf->dma_desc_pa, GFP_KERNEL);
> - if (!rbuf->dma_desc)
> - return -ENOMEM;
> + rbuf->n_desc = n_desc;
> + rbuf->dma_desc = dma_alloc_coherent(rga->dev,
> +     rbuf->n_desc * sizeof(*rbuf->dma_desc),
> +     &rbuf->dma_desc_pa, GFP_KERNEL);
> + if (!rbuf->dma_desc)
> + return -ENOMEM;
> + }
>
> return 0;
> }
> @@ -133,17 +136,21 @@ static int rga_buf_prepare(struct vb2_buffer *vb)
> for (i = 0; i < vb->num_planes; i++) {
> vb2_set_plane_payload(vb, i, f->pix.plane_fmt[i].sizeimage);
>
> - /* Create local MMU table for RGA */
> - n_desc = fill_descriptors(&rbuf->dma_desc[curr_desc],
> - rbuf->n_desc - curr_desc,
> - vb2_dma_sg_plane_desc(vb, i));
> - if (n_desc < 0) {
> - v4l2_err(&ctx->rga->v4l2_dev,
> - "Failed to map video buffer to RGA\n");
> - return n_desc;
> + if (rga_has_internal_iommu(ctx->rga)) {
> + /* Create local MMU table for RGA */
> + n_desc = fill_descriptors(&rbuf->dma_desc[curr_desc],
> + rbuf->n_desc - curr_desc,
> + vb2_dma_sg_plane_desc(vb, i));
> + if (n_desc < 0) {
> + v4l2_err(&ctx->rga->v4l2_dev,
> + "Failed to map video buffer to RGA\n");
> + return n_desc;
> + }
> + dma_addrs[i] = curr_desc << PAGE_SHIFT;
> + curr_desc += n_desc;
> + } else {
> + dma_addrs[i] = vb2_dma_contig_plane_dma_addr(vb, i);
> }
> - dma_addrs[i] = curr_desc << PAGE_SHIFT;
> - curr_desc += n_desc;
> }
>
> /* Fill the remaining planes */
> @@ -173,8 +180,9 @@ static void rga_buf_cleanup(struct vb2_buffer *vb)
> struct rga_ctx *ctx = vb2_get_drv_priv(vb->vb2_queue);
> struct rockchip_rga *rga = ctx->rga;
>
> - dma_free_coherent(rga->dev, rbuf->n_desc * sizeof(*rbuf->dma_desc),
> - rbuf->dma_desc, rbuf->dma_desc_pa);
> + if (rga_has_internal_iommu(rga))
> + dma_free_coherent(rga->dev, rbuf->n_desc * sizeof(*rbuf->dma_desc),
> + rbuf->dma_desc, rbuf->dma_desc_pa);
> }
>
> static void rga_buf_return_buffers(struct vb2_queue *q,
> diff --git a/drivers/media/platform/rockchip/rga/rga-hw.c b/drivers/media/platform/rockchip/rga/rga-hw.c
> index fe6f518aedd4e..fb0389ae8e132 100644
> --- a/drivers/media/platform/rockchip/rga/rga-hw.c
> +++ b/drivers/media/platform/rockchip/rga/rga-hw.c
> @@ -617,6 +617,7 @@ static struct rga_fmt formats[] = {
>
> const struct rga_hw rga2_hw = {
> .card_type = "rga2",
> + .has_internal_iommu = true,
> .formats = formats,
> .num_formats = ARRAY_SIZE(formats),
> .cmdbuf_size = RGA_CMDBUF_SIZE,
> diff --git a/drivers/media/platform/rockchip/rga/rga.c b/drivers/media/platform/rockchip/rga/rga.c
> index c9719c7bcfc1c..f28ec88c186fa 100644
> --- a/drivers/media/platform/rockchip/rga/rga.c
> +++ b/drivers/media/platform/rockchip/rga/rga.c
> @@ -23,6 +23,7 @@
> #include <media/v4l2-ioctl.h>
> #include <media/v4l2-mem2mem.h>
> #include <media/videobuf2-dma-sg.h>
> +#include <media/videobuf2-dma-contig.h>
> #include <media/videobuf2-v4l2.h>
>
> #include "rga.h"
> @@ -95,13 +96,16 @@ queue_init(void *priv, struct vb2_queue *src_vq, struct vb2_queue *dst_vq)
> src_vq->io_modes = VB2_MMAP | VB2_DMABUF;
> src_vq->drv_priv = ctx;
> src_vq->ops = &rga_qops;
> - src_vq->mem_ops = &vb2_dma_sg_memops;
> + src_vq->mem_ops = &vb2_dma_contig_memops;

That's a bit I'm less knowledgeable here, since I never used the sg_memops in
any of my work, but what is the consequence ? (appart from gaining external
iommu support)

> src_vq->gfp_flags = __GFP_DMA32;
> src_vq->buf_struct_size = sizeof(struct rga_vb_buffer);
> src_vq->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_COPY;
> src_vq->lock = &ctx->rga->mutex;
> src_vq->dev = ctx->rga->v4l2_dev.dev;
>
> + if (rga_has_internal_iommu(ctx->rga))
> + src_vq->mem_ops = &vb2_dma_sg_memops;
> +
> ret = vb2_queue_init(src_vq);
> if (ret)
> return ret;
> @@ -110,13 +114,16 @@ queue_init(void *priv, struct vb2_queue *src_vq, struct vb2_queue *dst_vq)
> dst_vq->io_modes = VB2_MMAP | VB2_DMABUF;
> dst_vq->drv_priv = ctx;
> dst_vq->ops = &rga_qops;
> - dst_vq->mem_ops = &vb2_dma_sg_memops;
> + dst_vq->mem_ops = &vb2_dma_contig_memops;
> dst_vq->gfp_flags = __GFP_DMA32;
> dst_vq->buf_struct_size = sizeof(struct rga_vb_buffer);
> dst_vq->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_COPY;
> dst_vq->lock = &ctx->rga->mutex;
> dst_vq->dev = ctx->rga->v4l2_dev.dev;
>
> + if (rga_has_internal_iommu(ctx->rga))
> + dst_vq->mem_ops = &vb2_dma_sg_memops;
> +
> return vb2_queue_init(dst_vq);
> }
>
> diff --git a/drivers/media/platform/rockchip/rga/rga.h b/drivers/media/platform/rockchip/rga/rga.h
> index 772f7dff9a8e5..fc81bc5562792 100644
> --- a/drivers/media/platform/rockchip/rga/rga.h
> +++ b/drivers/media/platform/rockchip/rga/rga.h
> @@ -148,6 +148,7 @@ static inline void rga_mod(struct rockchip_rga *rga, u32 reg, u32 val, u32 mask)
>
> struct rga_hw {
> const char *card_type;
> + bool has_internal_iommu;
> struct rga_fmt *formats;
> u32 num_formats;
> size_t cmdbuf_size;
> @@ -163,6 +164,11 @@ struct rga_hw {
> void (*get_version)(struct rockchip_rga *rga);
> };
>
> +static inline bool rga_has_internal_iommu(const struct rockchip_rga *rga)
> +{
> + return rga->hw->has_internal_iommu;
> +}
> +
> extern const struct rga_hw rga2_hw;
>
> #endif

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