Hi Andrzej!

Dne četrtek, 05. avgust 2021 ob 16:42:41 CEST je Andrzej Pietrasiewicz 
napisal(a):

Add the VP9 stateless decoder controls plus the documentation that goes
with it.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Co-developed-by: Ezequiel Garcia <redacted>
Signed-off-by: Ezequiel Garcia <redacted>
Signed-off-by: Adrian Ratiu <redacted>
Signed-off-by: Andrzej Pietrasiewicz <redacted>
Co-developed-by: Daniel Almeida <daniel.almeida@collabora.com>
Signed-off-by: Daniel Almeida <daniel.almeida@collabora.com>
---
 .../userspace-api/media/v4l/biblio.rst        |  10 +
 .../media/v4l/ext-ctrls-codec-stateless.rst   | 545 ++++++++++++++++++
 .../media/v4l/pixfmt-compressed.rst           |  15 +
 .../media/v4l/vidioc-g-ext-ctrls.rst          |   8 +
 .../media/v4l/vidioc-queryctrl.rst            |  12 +
 .../media/videodev2.h.rst.exceptions          |   2 +
 drivers/media/v4l2-core/v4l2-ctrls-core.c     | 174 ++++++
 drivers/media/v4l2-core/v4l2-ctrls-defs.c     |   8 +
 drivers/media/v4l2-core/v4l2-ioctl.c          |   1 +
 include/media/v4l2-ctrls.h                    |   4 +
 include/uapi/linux/v4l2-controls.h            | 433 ++++++++++++++
 include/uapi/linux/videodev2.h                |   6 +
 12 files changed, 1218 insertions(+)

<snip>

controls.h

additional

+ *	syntax elements that specify which mode and reference frame deltas 

are to be updated

+ *
+ * Those are the flags that may be passed to &v4l2_vp9_loop_filter.flags. See
+ * section '7.2.8 Loop filter semantics' of the VP9 specification for more
+ * details.
+ */
+enum v4l2_vp9_loop_filter_flags {
+	V4L2_VP9_LOOP_FILTER_FLAG_DELTA_ENABLED = 1 << 0,
+	V4L2_VP9_LOOP_FILTER_FLAG_DELTA_UPDATE = 1 << 1,
+};
+
+/**
+ * struct v4l2_vp9_loop_filter - VP9 loop filter parameters
+ *
+ * @ref_deltas: contains the adjustment needed for the filter level based on 

the chosen

+ *	reference frame. If this syntax element is not present in the 

bitstream, users

+ *	should pass its last value.
+ * @mode_deltas: contains the adjustment needed for the filter level based 

on the chosen mode.

+ *	If this syntax element is not present in the bitstream, users
+ *	should pass its last value.
+ * @level: indicates the loop filter strength
+ * @sharpness: indicates the sharpness level
+ * @flags: combination of V4L2_VP9_LOOP_FILTER_FLAG_* flags
+ * @reserved: padding field. Should be zeroed by applications.
+ *
+ * This structure contains all loop filter related parameters. See sections
+ * '7.2.8 Loop filter semantics' of the VP9 specification for more details.
+ */
+struct v4l2_vp9_loop_filter {
+	__s8 ref_deltas[4];
+	__s8 mode_deltas[2];
+	__u8 level;
+	__u8 sharpness;
+	__u8 flags;
+	__u8 reserved[7];
+};
+
+/**
+ * struct v4l2_vp9_quantization - VP9 quantization parameters
+ *
+ * @base_q_idx: indicates the base frame qindex
+ * @delta_q_y_dc: indicates the Y DC quantizer relative to base_q_idx
+ * @delta_q_uv_dc: indicates the UV DC quantizer relative to base_q_idx
+ * @delta_q_uv_ac: indicates the UV AC quantizer relative to base_q_idx
+ * @reserved: padding field. Should be zeroed by applications.
+ *
+ * Encodes the quantization parameters. See section '7.2.9 Quantization 

params

+ * syntax' of the VP9 specification for more details.
+ */
+struct v4l2_vp9_quantization {
+	__u8 base_q_idx;
+	__s8 delta_q_y_dc;
+	__s8 delta_q_uv_dc;
+	__s8 delta_q_uv_ac;
+	__u8 reserved[4];
+};
+
+/**
+ * enum v4l2_vp9_segmentation_flags - VP9 segmentation flags
+ *
+ * @V4L2_VP9_SEGMENTATION_FLAG_ENABLED: indicates that this frame makes use 

of

+ *	the segmentation tool
+ * @V4L2_VP9_SEGMENTATION_FLAG_UPDATE_MAP: indicates that the segmentation 

map

+ *	should be updated during the decoding of this frame
+ * @V4L2_VP9_SEGMENTATION_FLAG_TEMPORAL_UPDATE: indicates that the updates 

to

+ *	the segmentation map are coded relative to the existing 

segmentation map

+ * @V4L2_VP9_SEGMENTATION_FLAG_UPDATE_DATA: indicates that new parameters 

are

+ *	about to be specified for each segment
+ * @V4L2_VP9_SEGMENTATION_FLAG_ABS_OR_DELTA_UPDATE: indicates that the
+ *	segmentation parameters represent the actual values to be used
+ *
+ * Those are the flags that may be passed to &v4l2_vp9_segmentation.flags. 

See

+ * section '7.2.10 Segmentation params syntax' of the VP9 specification for
+ * more details.
+ */
+enum v4l2_vp9_segmentation_flags {
+	V4L2_VP9_SEGMENTATION_FLAG_ENABLED = 1 << 0,
+	V4L2_VP9_SEGMENTATION_FLAG_UPDATE_MAP = 1 << 1,
+	V4L2_VP9_SEGMENTATION_FLAG_TEMPORAL_UPDATE = 1 << 2,
+	V4L2_VP9_SEGMENTATION_FLAG_UPDATE_DATA = 1 << 3,
+	V4L2_VP9_SEGMENTATION_FLAG_ABS_OR_DELTA_UPDATE = 1 << 4,
+};
+
+#define V4L2_VP9_SEGMENT_FEATURE_ENABLED(id)	(1 << (id))
+#define V4L2_VP9_SEGMENT_FEATURE_ENABLED_MASK	0xf
+
+/**
+ * enum v4l2_vp9_segment_feature - VP9 segment feature IDs
+ *
+ * @V4L2_VP9_SEG_LVL_ALT_Q: quantizer segment feature
+ * @V4L2_VP9_SEG_LVL_ALT_L: loop filter segment feature
+ * @V4L2_VP9_SEG_LVL_REF_FRAME reference frame segment feature
+ * @V4L2_VP9_SEG_LVL_SKIP: skip segment feature
+ * @V4L2_VP9_SEG_LVV_MAX: number of segment features
+ *
+ * Segment feature IDs. See section '7.2.10 Segmentation params syntax' of 

the

+ * VP9 specification for more details.
+ */
+enum v4l2_vp9_segment_feature {
+	V4L2_VP9_SEG_LVL_ALT_Q,
+	V4L2_VP9_SEG_LVL_ALT_L,
+	V4L2_VP9_SEG_LVL_REF_FRAME,
+	V4L2_VP9_SEG_LVL_SKIP,
+	V4L2_VP9_SEG_LVL_MAX,
+};

What is the reason not to assign values like 1 << 0, 1 << 1, etc. and instead 
provide separate macro V4L2_VP9_SEGMENT_FEATURE_ENABLED()? This is a departure 
from current practice.

+
+/**
+ * struct v4l2_vp9_segmentation - VP9 segmentation parameters
+ *
+ * @feature_data: data attached to each feature. Data entry is only valid 

if the feature is enabled

+ * @feature_enabled: bitmask defining which features are enabled in each 

segment

+ * @tree_probs: specifies the probability values to be used when
+ *	decoding a Segment-ID. See '5.15. Segmentation map' section of the 

VP9 specification

+ *	for more details.
+ * @pred_probs: specifies the probability values to be used when decoding a
+ *	Predicted-Segment-ID. See '6.4.14. Get segment id syntax' section 

of :ref:`vp9`

+ *	for more details.
+ * @flags: combination of V4L2_VP9_SEGMENTATION_FLAG_* flags
+ * @reserved: padding field. Should be zeroed by applications.
+ *
+ * Encodes the quantization parameters. See section '7.2.10 Segmentation 

params syntax' of

+ * the VP9 specification for more details.
+ */
+struct v4l2_vp9_segmentation {
+	__s16 feature_data[8][4];
+	__u8 feature_enabled[8];
+	__u8 tree_probs[7];
+	__u8 pred_probs[3];
+	__u8 flags;
+	__u8 reserved[5];
+};
+
+/**
+ * enum v4l2_vp9_intra_prediction_mode - VP9 Intra prediction modes
+ *
+ * @V4L2_VP9_INTRA_PRED_MODE_DC_PRED: DC intra prediction
+ * @V4L2_VP9_INTRA_PRED_MODE_V_PRED: vertical intra prediction
+ * @V4L2_VP9_INTRA_PRED_MODE_H_PRED: horizontal intra prediction
+ * @V4L2_VP9_INTRA_PRED_MODE_D45_PRED: D45 intra prediction
+ * @V4L2_VP9_INTRA_PRED_MODE_D135_PRED: D135 intra prediction
+ * @V4L2_VP9_INTRA_PRED_MODE_D117_PRED: D117 intra prediction
+ * @V4L2_VP9_INTRA_PRED_MODE_D153_PRED: D153 intra prediction
+ * @V4L2_VP9_INTRA_PRED_MODE_D207_PRED: D207 intra prediction
+ * @V4L2_VP9_INTRA_PRED_MODE_D63_PRED: D63 intra prediction
+ * @V4L2_VP9_INTRA_PRED_MODE_TM_PRED: True Motion intra prediction
+ *
+ * See section '7.4.5 Intra frame mode info semantics' for more details.
+ */
+enum v4l2_vp9_intra_prediction_mode {
+	V4L2_VP9_INTRA_PRED_MODE_DC_PRED,
+	V4L2_VP9_INTRA_PRED_MODE_V_PRED,
+	V4L2_VP9_INTRA_PRED_MODE_H_PRED,
+	V4L2_VP9_INTRA_PRED_MODE_D45_PRED,
+	V4L2_VP9_INTRA_PRED_MODE_D135_PRED,
+	V4L2_VP9_INTRA_PRED_MODE_D117_PRED,
+	V4L2_VP9_INTRA_PRED_MODE_D153_PRED,
+	V4L2_VP9_INTRA_PRED_MODE_D207_PRED,
+	V4L2_VP9_INTRA_PRED_MODE_D63_PRED,
+	V4L2_VP9_INTRA_PRED_MODE_TM_PRED,
+};

I dislike using enums without assigning values. I see that historically (at 
the beginning of this file), values were always assigned. However, if 
maintainers agree with you, that's fine by me.

+
+/**
+ * enum v4l2_vp9_reset_frame_context - Valid values for
+ *			&v4l2_ctrl_vp9_frame->reset_frame_context
+ *
+ * @V4L2_VP9_RESET_FRAME_CTX_NONE: don't reset any frame context
+ * @V4L2_VP9_RESET_FRAME_CTX_SPEC: reset the frame context pointed by
+ *	&v4l2_ctrl_vp9_frame.frame_context_idx
+ * @V4L2_VP9_RESET_FRAME_CTX_ALL: reset all frame contexts
+ *
+ * See section '7.2 Uncompressed header semantics' of the VP9 specification 

for more details.

+ */
+enum v4l2_vp9_reset_frame_context {
+	V4L2_VP9_RESET_FRAME_CTX_NONE,
+	V4L2_VP9_RESET_FRAME_CTX_SPEC,
+	V4L2_VP9_RESET_FRAME_CTX_ALL,
+};
+
+/**
+ * enum v4l2_vp9_interpolation_filter - VP9 interpolation filter types
+ *
+ * @V4L2_VP9_INTERP_FILTER_EIGHTTAP: eight tap filter
+ * @V4L2_VP9_INTERP_FILTER_EIGHTTAP_SMOOTH: eight tap smooth filter
+ * @V4L2_VP9_INTERP_FILTER_EIGHTTAP_SHARP: eight tap sharp filter
+ * @V4L2_VP9_INTERP_FILTER_BILINEAR: bilinear filter
+ * @V4L2_VP9_INTERP_FILTER_SWITCHABLE: filter selection is signaled at the 

block level

+ *
+ * See section '7.2.7 Interpolation filter semantics' of the VP9 

specification

+ * for more details.
+ */
+enum v4l2_vp9_interpolation_filter {
+	V4L2_VP9_INTERP_FILTER_EIGHTTAP,
+	V4L2_VP9_INTERP_FILTER_EIGHTTAP_SMOOTH,
+	V4L2_VP9_INTERP_FILTER_EIGHTTAP_SHARP,
+	V4L2_VP9_INTERP_FILTER_BILINEAR,
+	V4L2_VP9_INTERP_FILTER_SWITCHABLE,
+};
+
+/**
+ * enum v4l2_vp9_reference_mode - VP9 reference modes
+ *
+ * @V4L2_VP9_REFERENCE_MODE_SINGLE_REFERENCE: indicates that all the inter 

blocks use only a

+ *	single reference frame to generate motion compensated prediction
+ * @V4L2_VP9_REFERENCE_MODE_COMPOUND_REFERENCE: requires all the inter 

blocks to use compound mode.

+ *	Single reference frame prediction is not allowed
+ * @V4L2_VP9_REFERENCE_MODE_SELECT: allows each individual inter block to 

select between single

+ *	and compound prediction modes
+ *
+ * See section '7.3.6 Frame reference mode semantics' of the VP9 

specification

+ * for more details.
+ */
+enum v4l2_vp9_reference_mode {
+	V4L2_VP9_REFERENCE_MODE_SINGLE_REFERENCE,
+	V4L2_VP9_REFERENCE_MODE_COMPOUND_REFERENCE,
+	V4L2_VP9_REFERENCE_MODE_SELECT,
+};
+
+/**
+ * enum v4l2_vp9_tx_mode - VP9 TX modes
+ *
+ * @V4L2_VP9_TX_MODE_ONLY_4X4: transform size is 4x4
+ * @V4L2_VP9_TX_MODE_ALLOW_8X8: transform size can be up to 8x8
+ * @V4L2_VP9_TX_MODE_ALLOW_16X16: transform size can be up to 16x16
+ * @V4L2_VP9_TX_MODE_ALLOW_32X32: transform size can be up to 32x32
+ * @V4L2_VP9_TX_MODE_SELECT: bitstream contains the transform size for each 

block

+ *
+ * See section '7.3.1 Tx mode semantics' of the VP9 specification for more 

details.

+ */
+enum v4l2_vp9_tx_mode {
+	V4L2_VP9_TX_MODE_ONLY_4X4,
+	V4L2_VP9_TX_MODE_ALLOW_8X8,
+	V4L2_VP9_TX_MODE_ALLOW_16X16,
+	V4L2_VP9_TX_MODE_ALLOW_32X32,
+	V4L2_VP9_TX_MODE_SELECT,
+};
+
+/**
+ * enum v4l2_vp9_frame_flags - VP9 frame flags
+ * @V4L2_VP9_FRAME_FLAG_KEY_FRAME: the frame is a key frame
+ * @V4L2_VP9_FRAME_FLAG_SHOW_FRAME: the frame should be displayed
+ * @V4L2_VP9_FRAME_FLAG_ERROR_RESILIENT: the decoding should be error 

resilient

+ * @V4L2_VP9_FRAME_FLAG_INTRA_ONLY: the frame does not reference other 

frames

+ * @V4L2_VP9_FRAME_FLAG_ALLOW_HIGH_PREC_MV: the frame can use high 

precision motion vectors

+ * @V4L2_VP9_FRAME_FLAG_REFRESH_FRAME_CTX: frame context should be updated 

after decoding

+ * @V4L2_VP9_FRAME_FLAG_PARALLEL_DEC_MODE: parallel decoding is used
+ * @V4L2_VP9_FRAME_FLAG_X_SUBSAMPLING: vertical subsampling is enabled
+ * @V4L2_VP9_FRAME_FLAG_Y_SUBSAMPLING: horizontal subsampling is enabled
+ * @V4L2_VP9_FRAME_FLAG_COLOR_RANGE_FULL_SWING: full UV range is used
+ *
+ * Check the VP9 specification for more details.
+ */
+enum v4l2_vp9_frame_flags {
+	V4L2_VP9_FRAME_FLAG_KEY_FRAME = 1 << 0,
+	V4L2_VP9_FRAME_FLAG_SHOW_FRAME = 1 << 1,
+	V4L2_VP9_FRAME_FLAG_ERROR_RESILIENT = 1 << 2,
+	V4L2_VP9_FRAME_FLAG_INTRA_ONLY = 1 << 3,
+	V4L2_VP9_FRAME_FLAG_ALLOW_HIGH_PREC_MV = 1 << 4,
+	V4L2_VP9_FRAME_FLAG_REFRESH_FRAME_CTX = 1 << 5,
+	V4L2_VP9_FRAME_FLAG_PARALLEL_DEC_MODE = 1 << 6,
+	V4L2_VP9_FRAME_FLAG_X_SUBSAMPLING = 1 << 7,
+	V4L2_VP9_FRAME_FLAG_Y_SUBSAMPLING = 1 << 8,
+	V4L2_VP9_FRAME_FLAG_COLOR_RANGE_FULL_SWING = 1 << 9,
+};
+
+/**
+ * enum v4l2_vp9_ref_frame_sign_bias - Whether ref_frame_sign_bias is 1 for 

a given reference frame

+ * @V4L2_VP9_SIGN_BIAS_LAST: ref_frame_sign_bias is 1 for the "last" 

reference frame

+ * @V4L2_VP9_SIGN_BIAS_GOLDEN: ref_frame_sign_bias is 1 for the "golden" 

reference frame

+ * @V4L2_VP9_SIGN_BIAS_ALT: ref_frame_sign_bias is 1 for the "alt" 

reference frame

+ */
+
+enum v4l2_vp9_ref_frame_sign_bias {
+	V4L2_VP9_SIGN_BIAS_LAST,
+	V4L2_VP9_SIGN_BIAS_GOLDEN,
+	V4L2_VP9_SIGN_BIAS_ALT,
+};

As I mentioned before, you probably want to assign values here, since values 
are used as bitmap.

+
+#define V4L2_VP9_PROFILE_MAX		3
+
+#define V4L2_CID_STATELESS_VP9_FRAME	(V4L2_CID_CODEC_STATELESS_BASE + 

300)

+/**
+ * struct v4l2_ctrl_vp9_frame - VP9 frame decoding control
+ *
+ * @lf: loop filter parameters. See &v4l2_vp9_loop_filter for more details
+ * @quant: quantization parameters. See &v4l2_vp9_quantization for more 

details

+ * @seg: segmentation parameters. See &v4l2_vp9_segmentation for more 

details

+ * @flags: combination of V4L2_VP9_FRAME_FLAG_* flags
+ * @compressed_header_size: compressed header size in bytes
+ * @uncompressed_header_size: uncompressed header size in bytes
+ * @frame_width_minus_1: add 1 to it and you'll get the frame width 

expressed in pixels

+ * @frame_height_minus_1: add 1 to it and you'll get the frame height 

expressed in pixels

+ * @render_width_minus_1: add 1 to it and you'll get the expected render 

width expressed in

+ *	pixels. This is not used during the decoding process but might be 

used by HW scalers

+ *	to prepare a frame that's ready for scanout
+ * @render_height_minus_1: add 1 to it and you'll get the expected render 

height expressed in

+ *	pixels. This is not used during the decoding process but might be 

used by HW scalers

+ *	to prepare a frame that's ready for scanout
+ * @last_frame_ts: "last" reference buffer timestamp.
+ * The timestamp refers to the timestamp field in struct v4l2_buffer.
+ * Use v4l2_timeval_to_ns() to convert the struct timeval to a __u64.
+ * @golden_frame_ts: "golden" reference buffer timestamp.
+ * The timestamp refers to the timestamp field in struct v4l2_buffer.
+ * Use v4l2_timeval_to_ns() to convert the struct timeval to a __u64.
+ * @alt_frame_ts: "alt" reference buffer timestamp.
+ * The timestamp refers to the timestamp field in struct v4l2_buffer.
+ * Use v4l2_timeval_to_ns() to convert the struct timeval to a __u64.
+ * @ref_frame_sign_bias: a bitfield specifying whether the sign bias is set 

for a given

+ *	reference frame. See &v4l2_vp9_ref_frame_sign_bias for more 

details.

+ * @reset_frame_context: specifies whether the frame context should be reset 

to default values.

+ *	See &v4l2_vp9_reset_frame_context for more details
+ * @frame_context_idx: frame context that should be used/updated
+ * @profile: VP9 profile. Can be 0, 1, 2 or 3
+ * @bit_depth: bits per components. Can be 8, 10 or 12. Note that not all 

profiles support

+ *	10 and/or 12 bits depths
+ * @interpolation_filter: specifies the filter selection used for performing 

inter prediction.

+ *	See &v4l2_vp9_interpolation_filter for more details
+ * @tile_cols_log2: specifies the base 2 logarithm of the width of each tile 

(where the width

+ *	is measured in units of 8x8 blocks). Shall be less than or equal 

to 6

+ * @tile_rows_log2: specifies the base 2 logarithm of the height of each 

tile (where the height

+ *	is measured in units of 8x8 blocks)
+ * @tx_mode: specifies the TX mode. See &v4l2_vp9_tx_mode for more details
+ * @reference_mode: specifies the type of inter prediction to be used. See
+ *	&v4l2_vp9_reference_mode for more details
+ * @reserved: padding field. Should be zeroed by applications.
+ */
+struct v4l2_ctrl_vp9_frame {
+	struct v4l2_vp9_loop_filter lf;
+	struct v4l2_vp9_quantization quant;
+	struct v4l2_vp9_segmentation seg;
+	__u32 flags;
+	__u16 compressed_header_size;
+	__u16 uncompressed_header_size;
+	__u16 frame_width_minus_1;
+	__u16 frame_height_minus_1;
+	__u16 render_width_minus_1;
+	__u16 render_height_minus_1;
+	__u64 last_frame_ts;
+	__u64 golden_frame_ts;
+	__u64 alt_frame_ts;
+	__u8 ref_frame_sign_bias;
+	__u8 reset_frame_context;
+	__u8 frame_context_idx;
+	__u8 profile;
+	__u8 bit_depth;
+	__u8 interpolation_filter;
+	__u8 tile_cols_log2;
+	__u8 tile_rows_log2;
+	__u8 tx_mode;

AFAICS, TX mode is part of compressed header in chapter 6.3.1. Any reason it's 
here and not in  v4l2_ctrl_vp9_compressed_hdr_probs?

+	__u8 reference_mode;
+	__u8 reserved[6];
+};
+
+#define V4L2_VP9_NUM_FRAME_CTX	4
+
+/**
+ * struct v4l2_vp9_mv_compressed_hdr_probs - VP9 Motion vector probability 

updates

+ * @joint: motion vector joint probability updates
+ * @sign: motion vector sign probability updates
+ * @classes: motion vector class probability updates
+ * @class0_bit: motion vector class0 bit probability updates
+ * @bits: motion vector bits probability updates
+ * @class0_fr: motion vector class0 fractional bit probability updates
+ * @fr: motion vector fractional bit probability updates
+ * @class0_hp: motion vector class0 high precision fractional bit 

probability updates

+ * @hp: motion vector high precision fractional bit probability updates
+ *
+ * This structure contains new values of motion vector probabilities.
+ * A value of zero in an array element means there is no update of the 

relevant probability.

+ * See `struct v4l2_vp9_prob_updates` for details.
+ */
+struct v4l2_vp9_mv_compressed_hdr_probs {
+	__u8 joint[3];
+	__u8 sign[2];
+	__u8 classes[2][10];
+	__u8 class0_bit[2];
+	__u8 bits[2][10];
+	__u8 class0_fr[2][2][3];
+	__u8 fr[2][3];
+	__u8 class0_hp[2];
+	__u8 hp[2];
+};
+
+#define V4L2_CID_STATELESS_VP9_COMPRESSED_HDR_PROBS	

(V4L2_CID_CODEC_STATELESS_BASE + 301)

+/**
+ * struct v4l2_ctrl_vp9_compressed_hdr_probs - VP9 probability updates 

control

+ * @tx8: TX 8x8 probability updates
+ * @tx16: TX 16x16 probability updates
+ * @tx32: TX 32x32 probability updates
+ * @coef: coefficient probability updates
+ * @skip: skip probability updates
+ * @inter_mode: inter mode probability updates
+ * @interp_filter: interpolation filter probability updates
+ * @is_inter: is inter-block probability updates
+ * @comp_mode: compound prediction mode probability updates
+ * @single_ref: single ref probability updates
+ * @comp_ref: compound ref probability updates
+ * @y_mode: Y prediction mode probability updates
+ * @uv_mode: UV prediction mode probability updates
+ * @partition: partition probability updates
+ * @mv: motion vector probability updates
+ *
+ * This structure holds the probabilities update as parsed in the 

compressed

+ * header (Spec 6.3). These values represent the value of probability 

update after

+ * being translated with inv_map_table[] (see 6.3.5). A value of zero in an 

array element

+ * means that there is no update of the relevant probability.
+ */
+struct v4l2_ctrl_vp9_compressed_hdr_probs {
+	__u8 tx8[2][1];
+	__u8 tx16[2][2];
+	__u8 tx32[2][3];
+	__u8 coef[4][2][2][6][6][3];
+	__u8 skip[3];
+	__u8 inter_mode[7][3];
+	__u8 interp_filter[4][2];
+	__u8 is_inter[4];
+	__u8 comp_mode[5];
+	__u8 single_ref[5][2];
+	__u8 comp_ref[5];
+	__u8 y_mode[4][9];
+	__u8 uv_mode[10][9];
+	__u8 partition[16][3];
+
+	struct v4l2_vp9_mv_compressed_hdr_probs mv;

v4l2_ctrl_vp9_compressed_hdr_probs and v4l2_vp9_mv_compressed_hdr_probs are so 
confusingly similar, it's easy to mess up quickly. Can we find more distinct 
names?

Note, I just skimmed this patch, maybe I'll have some more questions later. 
Great work!

Best regards,
Jernej

frame */

 #define V4L2_PIX_FMT_VP9      v4l2_fourcc('V', 'P', '9', '0') /* VP9 */
+#define V4L2_PIX_FMT_VP9_FRAME v4l2_fourcc('V', 'P', '9', 'F') /* VP9 parsed 

frame */

 #define V4L2_PIX_FMT_HEVC     v4l2_fourcc('H', 'E', 'V', 'C') /* HEVC aka H.

265 */

 #define V4L2_PIX_FMT_FWHT     v4l2_fourcc('F', 'W', 'H', 'T') /* Fast Walsh 

Hadamard Transform (vicodec) */

 #define V4L2_PIX_FMT_FWHT_STATELESS     v4l2_fourcc('S', 'F', 'W', 'H') /* 

Stateless FWHT (vicodec) */

*p_mpeg2_sequence;

 		struct v4l2_ctrl_mpeg2_picture __user *p_mpeg2_picture;
 		struct v4l2_ctrl_mpeg2_quantisation __user 

*p_mpeg2_quantisation;

+		struct v4l2_ctrl_vp9_compressed_hdr_probs __user 

*p_vp9_compressed_hdr_probs;