[PATCH v13 16/17] media: uapi: Change data_bit_offset definition

Benjamin Gaignard
2022-07-08T16:30:17Z

'F.7.3.6.1 General slice segment header syntax' section of HEVC
specification describes that a slice header always end aligned on
byte boundary, therefore we only need to provide the data offset in bytes.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Reviewed-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Acked-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Tested-by: Jernej Skrabec <jernej.skrabec@gmail.com>
---
.../media/v4l/ext-ctrls-codec.rst | 4 ++--
.../staging/media/sunxi/cedrus/cedrus_h265.c | 19 ++++++++++++++++++-
.../staging/media/sunxi/cedrus/cedrus_video.c | 1 -
include/media/hevc-ctrls.h | 4 ++--
4 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
index 73b347acb704..6cf68588af1b 100644
--- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
+++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
@@ -3008,8 +3008,8 @@ enum v4l2_mpeg_video_hevc_size_of_length_field -
- ``bit_size``
- Size (in bits) of the current slice data.
* - __u32
- - ``data_bit_offset``
- - Offset (in bits) to the video data in the current slice data.
+ - ``data_byte_offset``
+ - Offset (in bytes) to the video data in the current slice data.
* - __u32
- ``num_entry_point_offsets``
- Specifies the number of entry point offset syntax elements in the slice header.
diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
index 411601975124..7b67cb4621cf 100644
--- a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
+++ b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
@@ -317,6 +317,8 @@ static void cedrus_h265_setup(struct cedrus_ctx *ctx,
u32 chroma_log2_weight_denom;
u32 output_pic_list_index;
u32 pic_order_cnt[2];
+ u8 *padding;
+ int count;
u32 reg;

sps = run->h265.sps;
@@ -405,7 +407,22 @@ static void cedrus_h265_setup(struct cedrus_ctx *ctx,
/* Initialize bitstream access. */
cedrus_write(dev, VE_DEC_H265_TRIGGER, VE_DEC_H265_TRIGGER_INIT_SWDEC);

- cedrus_h265_skip_bits(dev, slice_params->data_bit_offset);
+ /*
+ * Cedrus expects that bitstream pointer is actually at the end of the slice header
+ * instead of start of slice data. Padding is 8 bits at most (one bit set to 1 and
+ * at most seven bits set to 0), so we have to inspect only one byte before slice data.
+ */
+ padding = (u8 *)vb2_plane_vaddr(&run->src->vb2_buf, 0) +
+ slice_params->data_byte_offset - 1;
+
+ for (count = 0; count < 8; count++)
+ if (*padding & (1 << count))
+ break;
+
+ /* Include the one bit. */
+ count++;
+
+ cedrus_h265_skip_bits(dev, slice_params->data_byte_offset * 8 - count);

/* Bitstream parameters. */

diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_video.c b/drivers/staging/media/sunxi/cedrus/cedrus_video.c
index 33726175d980..66714609b577 100644
--- a/drivers/staging/media/sunxi/cedrus/cedrus_video.c
+++ b/drivers/staging/media/sunxi/cedrus/cedrus_video.c
@@ -568,7 +568,6 @@ int cedrus_queue_init(void *priv, struct vb2_queue *src_vq,

src_vq->type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
src_vq->io_modes = VB2_MMAP | VB2_DMABUF;
- src_vq->dma_attrs = DMA_ATTR_NO_KERNEL_MAPPING;
src_vq->drv_priv = ctx;
src_vq->buf_struct_size = sizeof(struct cedrus_buffer);
src_vq->ops = &cedrus_qops;
diff --git a/include/media/hevc-ctrls.h b/include/media/hevc-ctrls.h
index 7358cbfc3e4d..c89029b3c5da 100644
--- a/include/media/hevc-ctrls.h
+++ b/include/media/hevc-ctrls.h
@@ -310,7 +310,7 @@ struct v4l2_hevc_pred_weight_table {
* V4L2_CTRL_FLAG_DYNAMIC_ARRAY flag must be set when using it.
*
* @bit_size: size (in bits) of the current slice data
- * @data_bit_offset: offset (in bits) to the video data in the current slice data
+ * @data_byte_offset: offset (in bytes) to the video data in the current slice data
* @num_entry_point_offsets: specifies the number of entry point offset syntax
* elements in the slice header.
* @nal_unit_type: specifies the coding type of the slice (B, P or I)
@@ -356,7 +356,7 @@ struct v4l2_hevc_pred_weight_table {
*/
struct v4l2_ctrl_hevc_slice_params {
__u32 bit_size;
- __u32 data_bit_offset;
+ __u32 data_byte_offset;
__u32 num_entry_point_offsets;
/* ISO/IEC 23008-2, ITU-T Rec. H.265: NAL unit header */
__u8 nal_unit_type;