[PATCH v5 18/29] media: rockchip: rga: check scaling factor
Nicolas Dufresne
nicolas at ndufresne.ca
Fri May 8 16:11:53 PDT 2026
Le mardi 28 avril 2026 à 11:00 +0200, Sven Püschel a écrit :
> Check the scaling factor to avoid potential problems. This is relevant
> for the upcoming RGA3 support, as it can hang when the scaling factor
> is exceeded.
>
> There are two relevant scenarios that have to be considered to protect
> against invalid scaling values:
>
> When the output or capture is already streaming, setting the format on
> the other side should consider the max scaling factor and clamp it
> accordingly. This is only done in the streaming case, as it otherwise
> may unintentionally clamp the value when the application sets the first
> format (due to a default format on the other side).
>
> When the format is set on both sides first, then the format won't be
> corrected by above means. Therefore the second streamon call has to
> check the scaling factor and fail otherwise.
>
> As try functions should only be state aware if specified, the scaling
> limitation is only done in s_fmt.
>
> Signed-off-by: Sven Püschel <s.pueschel at pengutronix.de>
> ---
> drivers/media/platform/rockchip/rga/rga-hw.c | 1 +
> drivers/media/platform/rockchip/rga/rga-hw.h | 1 +
> drivers/media/platform/rockchip/rga/rga.c | 47 ++++++++++++++++++++++++++++
> drivers/media/platform/rockchip/rga/rga.h | 1 +
> 4 files changed, 50 insertions(+)
>
> diff --git a/drivers/media/platform/rockchip/rga/rga-hw.c b/drivers/media/platform/rockchip/rga/rga-hw.c
> index 11079477a3008..11a1a914668f6 100644
> --- a/drivers/media/platform/rockchip/rga/rga-hw.c
> +++ b/drivers/media/platform/rockchip/rga/rga-hw.c
> @@ -595,6 +595,7 @@ const struct rga_hw rga2_hw = {
> .max_width = MAX_WIDTH,
> .min_height = MIN_HEIGHT,
> .max_height = MAX_HEIGHT,
> + .max_scaling_factor = MAX_SCALING_FACTOR,
> .stride_alignment = 4,
>
> .setup_cmdbuf = rga_hw_setup_cmdbuf,
> diff --git a/drivers/media/platform/rockchip/rga/rga-hw.h b/drivers/media/platform/rockchip/rga/rga-hw.h
> index c2e34be751939..805ec23e5e3f4 100644
> --- a/drivers/media/platform/rockchip/rga/rga-hw.h
> +++ b/drivers/media/platform/rockchip/rga/rga-hw.h
> @@ -14,6 +14,7 @@
>
> #define MIN_WIDTH 34
> #define MIN_HEIGHT 34
> +#define MAX_SCALING_FACTOR 16
>
> #define RGA_TIMEOUT 500
>
> diff --git a/drivers/media/platform/rockchip/rga/rga.c b/drivers/media/platform/rockchip/rga/rga.c
> index d111b348255e2..75d05c86b1c00 100644
> --- a/drivers/media/platform/rockchip/rga/rga.c
> +++ b/drivers/media/platform/rockchip/rga/rga.c
> @@ -405,10 +405,36 @@ static int vidioc_s_fmt(struct file *file, void *priv, struct v4l2_format *f)
> struct v4l2_pix_format_mplane *pix_fmt = &f->fmt.pix_mp;
> struct rga_ctx *ctx = file_to_rga_ctx(file);
> struct rockchip_rga *rga = ctx->rga;
> + const struct rga_hw *hw = rga->hw;
> struct vb2_queue *vq;
> struct rga_frame *frm;
> int ret = 0;
> int i;
> + struct rga_frame *limit_frm = NULL;
> +
> + /* Limit before try_fmt to avoid recalculating the stride */
> + if (V4L2_TYPE_IS_OUTPUT(f->type) &&
> + v4l2_m2m_get_dst_vq(ctx->fh.m2m_ctx)->streaming)
> + limit_frm = &ctx->out;
If you need to, use helpers such as vb2_is_streaming(), though in this case, I
think you want to use vb2_is_busy(), which protects against changing the format
of a queue that is already allocated. This is needed because drivers, except vp9
and av1 stateless decoders, don't track the format per buffer.
> + if (V4L2_TYPE_IS_CAPTURE(f->type) &&
> + v4l2_m2m_get_src_vq(ctx->fh.m2m_ctx)->streaming)
Same.
> + limit_frm = &ctx->in;
> + if (limit_frm) {
> + const struct v4l2_frmsize_stepwise frmsize = {
> + .min_width = DIV_ROUND_UP(limit_frm->pix.width,
> + hw->max_scaling_factor),
> + .max_width =
> + limit_frm->pix.width * hw->max_scaling_factor,
Shouldn't you control the absolute min/max for this IP ?
> + .min_height = DIV_ROUND_UP(limit_frm->pix.height,
> + hw->max_scaling_factor),
> + .max_height =
> + limit_frm->pix.height * hw->max_scaling_factor,
> + .step_width = 1,
> + .step_height = 1,
Shouldn't that step match the subsampling like you did earlier ?
Nicolas
> + };
> + v4l2_apply_frmsize_constraints(&pix_fmt->width,
> + &pix_fmt->height, &frmsize);
> + }
>
> /* Adjust all values accordingly to the hardware capabilities
> * and chosen format.
> @@ -568,12 +594,33 @@ static int vidioc_s_selection(struct file *file, void *priv,
> return ret;
> }
>
> +static bool check_scaling(const struct rga_hw *hw, u32 src_size, u32 dst_size)
> +{
> + if (src_size < dst_size)
> + return src_size * hw->max_scaling_factor >= dst_size;
> + else
> + return dst_size * hw->max_scaling_factor >= src_size;
> +}
> +
> static int vidioc_streamon(struct file *file, void *priv,
> enum v4l2_buf_type type)
> {
> struct rga_ctx *ctx = file_to_rga_ctx(file);
> const struct rga_hw *hw = ctx->rga->hw;
>
> + if ((V4L2_TYPE_IS_OUTPUT(type) &&
> + v4l2_m2m_get_dst_vq(ctx->fh.m2m_ctx)->streaming) ||
> + (V4L2_TYPE_IS_CAPTURE(type) &&
> + v4l2_m2m_get_src_vq(ctx->fh.m2m_ctx)->streaming)) {
> + /*
> + * As the other side is already streaming,
> + * check that the max scaling factor isn't exceeded.
> + */
> + if (!check_scaling(hw, ctx->in.pix.width, ctx->out.pix.width) ||
> + !check_scaling(hw, ctx->in.pix.height, ctx->out.pix.height))
> + return -EINVAL;
> + }
> +
> hw->setup_cmdbuf(ctx);
>
> return v4l2_m2m_streamon(file, ctx->fh.m2m_ctx, type);
> diff --git a/drivers/media/platform/rockchip/rga/rga.h b/drivers/media/platform/rockchip/rga/rga.h
> index c741213710b32..454af283b1694 100644
> --- a/drivers/media/platform/rockchip/rga/rga.h
> +++ b/drivers/media/platform/rockchip/rga/rga.h
> @@ -150,6 +150,7 @@ struct rga_hw {
> size_t cmdbuf_size;
> u32 min_width, min_height;
> u32 max_width, max_height;
> + u8 max_scaling_factor;
> u8 stride_alignment;
>
> void (*setup_cmdbuf)(struct rga_ctx *ctx);
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