Re: [PATCH v3 02/15] media: v4l2-ctrls: Add hevc_ext_sps_[ls]t_rps controls

[Detlev Casanova <detlev.casanova@collabora.com>]

Hi Nicolas,

On 12/10/25 15:07, Nicolas Dufresne wrote:
> Hi,
>
> Le mercredi 22 octobre 2025 à 12:22 -0400, Detlev Casanova a écrit :
>> The vdpu381 decoder found on newer Rockchip SoC need the information
>> from the long term and short term ref pic sets from the SPS.
>>
>> So far, it wasn't included in the v4l2 API, so add it with new dynamic
>> sized controls.
>>
>> Each element of the hevc_ext_sps_lt_rps array contains the long term ref
>> pic set at that index.
>> Each element of the hevc_ext_sps_st_rps contains the short term ref pic
>> set at that index, as the raw data.
>> It is the role of the drivers to calculate the reference sets values.
>>
>> Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
>> ---
>>   drivers/media/v4l2-core/v4l2-ctrls-core.c | 18 +++++++
>>   drivers/media/v4l2-core/v4l2-ctrls-defs.c | 10 ++++
>>   include/uapi/linux/v4l2-controls.h        | 61 +++++++++++++++++++++++
>>   include/uapi/linux/videodev2.h            |  2 +
>>   4 files changed, 91 insertions(+)
>>
>> diff --git a/drivers/media/v4l2-core/v4l2-ctrls-core.c b/drivers/media/v4l2-core/v4l2-ctrls-core.c
>> index 85d07ef44f62..779936727505 100644
>> --- a/drivers/media/v4l2-core/v4l2-ctrls-core.c
>> +++ b/drivers/media/v4l2-core/v4l2-ctrls-core.c
>> @@ -418,6 +418,12 @@ void v4l2_ctrl_type_op_log(const struct v4l2_ctrl *ctrl)
>>   	case V4L2_CTRL_TYPE_HEVC_SLICE_PARAMS:
>>   		pr_cont("HEVC_SLICE_PARAMS");
>>   		break;
>> +	case V4L2_CTRL_TYPE_HEVC_EXT_SPS_ST_RPS:
>> +		pr_cont("HEVC_EXT_SPS_ST_RPS");
>> +		break;
>> +	case V4L2_CTRL_TYPE_HEVC_EXT_SPS_LT_RPS:
>> +		pr_cont("HEVC_EXT_SPS_LT_RPS");
>> +		break;
>>   	case V4L2_CTRL_TYPE_HEVC_SCALING_MATRIX:
>>   		pr_cont("HEVC_SCALING_MATRIX");
>>   		break;
>> @@ -1173,6 +1179,12 @@ static int std_validate_compound(const struct v4l2_ctrl *ctrl, u32 idx,
>>   	case V4L2_CTRL_TYPE_HEVC_SLICE_PARAMS:
>>   		break;
>>   
>> +	case V4L2_CTRL_TYPE_HEVC_EXT_SPS_ST_RPS:
>> +		break;
>> +
>> +	case V4L2_CTRL_TYPE_HEVC_EXT_SPS_LT_RPS:
>> +		break;
>> +
>>   	case V4L2_CTRL_TYPE_HDR10_CLL_INFO:
>>   		break;
>>   
>> @@ -1925,6 +1937,12 @@ static struct v4l2_ctrl *v4l2_ctrl_new(struct v4l2_ctrl_handler *hdl,
>>   	case V4L2_CTRL_TYPE_HEVC_SLICE_PARAMS:
>>   		elem_size = sizeof(struct v4l2_ctrl_hevc_slice_params);
>>   		break;
>> +	case V4L2_CTRL_TYPE_HEVC_EXT_SPS_ST_RPS:
>> +		elem_size = sizeof(struct v4l2_ctrl_hevc_ext_sps_st_rps);
>> +		break;
>> +	case V4L2_CTRL_TYPE_HEVC_EXT_SPS_LT_RPS:
>> +		elem_size = sizeof(struct v4l2_ctrl_hevc_ext_sps_lt_rps);
>> +		break;
>>   	case V4L2_CTRL_TYPE_HEVC_SCALING_MATRIX:
>>   		elem_size = sizeof(struct v4l2_ctrl_hevc_scaling_matrix);
>>   		break;
>> diff --git a/drivers/media/v4l2-core/v4l2-ctrls-defs.c b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
>> index ad41f65374e2..167286c9e424 100644
>> --- a/drivers/media/v4l2-core/v4l2-ctrls-defs.c
>> +++ b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
>> @@ -1233,6 +1233,8 @@ const char *v4l2_ctrl_get_name(u32 id)
>>   	case V4L2_CID_STATELESS_HEVC_DECODE_MODE:		return "HEVC Decode Mode";
>>   	case V4L2_CID_STATELESS_HEVC_START_CODE:		return "HEVC Start Code";
>>   	case V4L2_CID_STATELESS_HEVC_ENTRY_POINT_OFFSETS:	return "HEVC Entry Point Offsets";
>> +	case V4L2_CID_STATELESS_HEVC_EXT_SPS_ST_RPS:		return "HEVC Short Term Ref Sets";
>> +	case V4L2_CID_STATELESS_HEVC_EXT_SPS_LT_RPS:		return "HEVC Long Term Ref Sets";
>>   	case V4L2_CID_STATELESS_AV1_SEQUENCE:			return "AV1 Sequence Parameters";
>>   	case V4L2_CID_STATELESS_AV1_TILE_GROUP_ENTRY:		return "AV1 Tile Group Entry";
>>   	case V4L2_CID_STATELESS_AV1_FRAME:			return "AV1 Frame Parameters";
>> @@ -1578,6 +1580,14 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
>>   		*type = V4L2_CTRL_TYPE_U32;
>>   		*flags |= V4L2_CTRL_FLAG_DYNAMIC_ARRAY;
>>   		break;
>> +	case V4L2_CID_STATELESS_HEVC_EXT_SPS_ST_RPS:
>> +		*type = V4L2_CTRL_TYPE_HEVC_EXT_SPS_ST_RPS;
>> +		*flags |= V4L2_CTRL_FLAG_DYNAMIC_ARRAY;
>> +		break;
>> +	case V4L2_CID_STATELESS_HEVC_EXT_SPS_LT_RPS:
>> +		*type = V4L2_CTRL_TYPE_HEVC_EXT_SPS_LT_RPS;
>> +		*flags |= V4L2_CTRL_FLAG_DYNAMIC_ARRAY;
>> +		break;
>>   	case V4L2_CID_STATELESS_VP9_COMPRESSED_HDR:
>>   		*type = V4L2_CTRL_TYPE_VP9_COMPRESSED_HDR;
>>   		break;
>> diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
>> index 2d30107e047e..dd9e29afa155 100644
>> --- a/include/uapi/linux/v4l2-controls.h
>> +++ b/include/uapi/linux/v4l2-controls.h
>> @@ -2093,6 +2093,8 @@ struct v4l2_ctrl_mpeg2_quantisation {
>>   #define V4L2_CID_STATELESS_HEVC_DECODE_MODE	(V4L2_CID_CODEC_STATELESS_BASE + 405)
>>   #define V4L2_CID_STATELESS_HEVC_START_CODE	(V4L2_CID_CODEC_STATELESS_BASE + 406)
>>   #define V4L2_CID_STATELESS_HEVC_ENTRY_POINT_OFFSETS (V4L2_CID_CODEC_STATELESS_BASE + 407)
>> +#define V4L2_CID_STATELESS_HEVC_EXT_SPS_ST_RPS  (V4L2_CID_CODEC_STATELESS_BASE + 408)
>> +#define V4L2_CID_STATELESS_HEVC_EXT_SPS_LT_RPS  (V4L2_CID_CODEC_STATELESS_BASE + 409)
>>   
>>   enum v4l2_stateless_hevc_decode_mode {
>>   	V4L2_STATELESS_HEVC_DECODE_MODE_SLICE_BASED,
>> @@ -2548,6 +2550,65 @@ struct v4l2_ctrl_hevc_scaling_matrix {
>>   	__u8	scaling_list_dc_coef_32x32[2];
>>   };
>>   
>> +#define V4L2_HEVC_EXT_SPS_ST_RPS_FLAG_INTER_REF_PIC_SET_PRED	0x1
>> +
>> +/*
>> + * struct v4l2_ctrl_hevc_ext_sps_st_rps - HEVC short term RPS parameters
>> + *
>> + * Dynamic size 1-dimension array for short term RPS. The number of elements
>> + * is v4l2_ctrl_hevc_sps::num_short_term_ref_pic_sets. It can contain up to 65 elements.
>> + *
>> + * @delta_idx_minus1: Specifies the delta compare to the index. See details in section 7.4.8
>> + *                    "Short-term reference picture set semantics" of the specification.
>> + * @delta_rps_sign: Sign of the delta as specified in section 7.4.8 "Short-term reference picture
>> + *                  set semantics" of the specification.
>> + * @abs_delta_rps_minus1: Absolute delta RPS as specified in section 7.4.8 "Short-term reference
>> + *                        picture set semantics" of the specification.
>> + * @num_negative_pics: Number of short-term RPS entries that have picture order count values less
>> + *                     than the picture order count value of the current picture.
>> + * @num_positive_pics: Number of short-term RPS entries that have picture order count values
>> + *                     greater than the picture order count value of the current picture.
>> + * @used_by_curr_pic: Bit j specifies if short-term RPS j is used by the current picture.
>> + * @use_delta_flag: Bit j equals to 1 specifies that the j-th entry in the source candidate
>> + *                  short-term RPS is included in this candidate short-term RPS.
>> + * @delta_poc_s0_minus1: Specifies the negative picture order count delta for the i-th entry in
>> + *                       the short-term RPS. See details in section 7.4.8 "Short-term reference
>> + *                       picture set semantics" of the specification.
>> + * @delta_poc_s1_minus1: Specifies the positive picture order count delta for the i-th entry in
>> + *                       the short-term RPS. See details in section 7.4.8 "Short-term reference
>> + *                       picture set semantics" of the specification.
>> + * @flags: See V4L2_HEVC_EXT_SPS_ST_RPS_FLAG_{}
>> + */
>> +struct v4l2_ctrl_hevc_ext_sps_st_rps {
>> +	__u8	delta_idx_minus1;
>> +	__u8	delta_rps_sign;
>> +	__u16	abs_delta_rps_minus1;
>> +	__u8	num_negative_pics;
>> +	__u8	num_positive_pics;
>> +	__u32	used_by_curr_pic;
> Did you run pahole ? This one does not seem to align, it starts with 16bit
> offset. The remark is because 32bit and 64bit platform, and all compiler should
> have the same binary representation, otherwise it will break in some ways.

That's a good point. I moved abs_delta_rps_minus1 with the other __u16 
fields and changed flags to be 16 bits too.

Also changed flags to 16 bits in v4l2_ctrl_hevc_ext_sps_lt_rps.

> regards,
> Nicolas
>
>> +	__u32	use_delta_flag;
>> +	__u16	delta_poc_s0_minus1[16];
>> +	__u16	delta_poc_s1_minus1[16];
>> +	__u8	flags;
>> +};
>> +
>> +#define V4L2_HEVC_EXT_SPS_LT_RPS_FLAG_USED_LT		0x1
>> +
>> +/*
>> + * struct v4l2_ctrl_hevc_ext_sps_lt_rps - HEVC long term RPS parameters
>> + *
>> + * Dynamic size 1-dimension array for long term RPS. The number of elements
>> + * is v4l2_ctrl_hevc_sps::num_long_term_ref_pics_sps. It can contain up to 65 elements.
>> + *
>> + * @lt_ref_pic_poc_lsb_sps: picture order count modulo MaxPicOrderCntLsb of the i-th candidate
>> + *                          long-term reference picture.
>> + * @flags: See V4L2_HEVC_EXT_SPS_LT_RPS_FLAG_{}
>> + */
>> +struct v4l2_ctrl_hevc_ext_sps_lt_rps {
>> +	__u16	lt_ref_pic_poc_lsb_sps;
>> +	__u8	flags;
>> +};
>> +
>>   /* Stateless VP9 controls */
>>   
>>   #define V4L2_VP9_LOOP_FILTER_FLAG_DELTA_ENABLED	0x1
>> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
>> index becd08fdbddb..ae1d33fd37b7 100644
>> --- a/include/uapi/linux/videodev2.h
>> +++ b/include/uapi/linux/videodev2.h
>> @@ -1981,6 +1981,8 @@ enum v4l2_ctrl_type {
>>   	V4L2_CTRL_TYPE_HEVC_SLICE_PARAMS	= 0x0272,
>>   	V4L2_CTRL_TYPE_HEVC_SCALING_MATRIX	= 0x0273,
>>   	V4L2_CTRL_TYPE_HEVC_DECODE_PARAMS	= 0x0274,
>> +	V4L2_CTRL_TYPE_HEVC_EXT_SPS_ST_RPS	= 0x0275,
>> +	V4L2_CTRL_TYPE_HEVC_EXT_SPS_LT_RPS	= 0x0276,
>>   
>>   	V4L2_CTRL_TYPE_AV1_SEQUENCE	    = 0x280,
>>   	V4L2_CTRL_TYPE_AV1_TILE_GROUP_ENTRY = 0x281,

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