Re: [PATCH v5 2/5] media: v4l2-core: Add support for video encoder ROI control

[Deepa Guthyappa Madivalara <deepa.madivalara@oss.qualcomm.com>]

On 9/10/2026 12:49 AM, Hans Verkuil wrote:
> On 15/08/2026 21:22, Deepa Guthyappa Madivalara wrote:
>> Add necessary support for controls V4L2_CID_MPEG_VIDEO_ROI_MB_DELTA_QP
>> and V4L2_CID_MPEG_VIDEO_ROI_MB_SIZE.
> See my comment at the end of patch 1/5: this split should be done differently,
> the first patch adds V4L2_CTRL_TYPE_S8 support, the second adds support for
> the new controls.
Upated in v6.
>> Signed-off-by: Deepa Guthyappa Madivalara<deepa.madivalara@oss.qualcomm.com>
>> ---
>>   drivers/media/v4l2-core/v4l2-ctrls-api.c  |  1 +
>>   drivers/media/v4l2-core/v4l2-ctrls-core.c | 23 ++++++++++++++++++++++-
>>   drivers/media/v4l2-core/v4l2-ctrls-defs.c | 10 ++++++++++
>>   include/media/v4l2-ctrls.h                |  3 ++-
>>   4 files changed, 35 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/media/v4l2-core/v4l2-ctrls-api.c b/drivers/media/v4l2-core/v4l2-ctrls-api.c
>> index 93d8d4012d0f4fef004e417d0aee2ae44b1b30bd..7d41cfd7378baaa929d4da0266c45f731bb54285 100644
>> --- a/drivers/media/v4l2-core/v4l2-ctrls-api.c
>> +++ b/drivers/media/v4l2-core/v4l2-ctrls-api.c
>> @@ -980,6 +980,7 @@ int __v4l2_ctrl_modify_range(struct v4l2_ctrl *ctrl,
>>   	case V4L2_CTRL_TYPE_U8:
>>   	case V4L2_CTRL_TYPE_U16:
>>   	case V4L2_CTRL_TYPE_U32:
>> +	case V4L2_CTRL_TYPE_S8:
>>   		if (ctrl->is_array)
>>   			return -EINVAL;
>>   		ret = check_range(ctrl->type, min, max, step, def);
>> diff --git a/drivers/media/v4l2-core/v4l2-ctrls-core.c b/drivers/media/v4l2-core/v4l2-ctrls-core.c
>> index 5b8a594fb9e24e16128c9c763a3b1dd311fad2ba..db6577070ebd2eb6a60599b3b2394fe128236705 100644
>> --- a/drivers/media/v4l2-core/v4l2-ctrls-core.c
>> +++ b/drivers/media/v4l2-core/v4l2-ctrls-core.c
>> @@ -290,6 +290,14 @@ static void __v4l2_ctrl_type_op_init(const struct v4l2_ctrl *ctrl, u32 from_idx,
>>   			memset(ptr.p_u32 + from_idx, 0, elems * sizeof(u32));
>>   		}
>>   		break;
>> +	case V4L2_CTRL_TYPE_S8:
>> +		if (value) {
>> +			for (i = from_idx; i < tot_elems; i++)
>> +				ptr.p_s8[i] = value;
>> +		} else {
>> +			memset(ptr.p_s8 + from_idx, 0, elems * sizeof(s8));
> It's a single byte, so you can just do memset with 'value'. Just cast value to u8.
>
>> +		}
>> +		break;
>>   	default:
>>   		for (i = from_idx; i < tot_elems; i++) {
>>   			switch (which) {
>> @@ -370,6 +378,9 @@ void v4l2_ctrl_type_op_log(const struct v4l2_ctrl *ctrl)
>>   	case V4L2_CTRL_TYPE_U32:
>>   		pr_cont("%u", (unsigned)*ptr.p_u32);
>>   		break;
>> +	case V4L2_CTRL_TYPE_S8:
>> +		pr_cont("%d", *ptr.p_s8);
>> +		break;
>>   	case V4L2_CTRL_TYPE_AREA:
>>   		pr_cont("%ux%u", ptr.p_area->width, ptr.p_area->height);
>>   		break;
>> @@ -1397,6 +1408,8 @@ static int std_validate_compound(const struct v4l2_ctrl *ctrl, u32 idx,
>>   			return -EINVAL;
>>   		break;
>>   
>> +	case V4L2_CID_MPEG_VIDEO_ROI_MB_DELTA_QP:
>> +		break;
>>   	default:
>>   		return -EINVAL;
>>   	}
>> @@ -1410,6 +1423,7 @@ static int std_validate_elem(const struct v4l2_ctrl *ctrl, u32 idx,
>>   	size_t len;
>>   	u64 offset;
>>   	s64 val;
>> +	s32 tmp;
>>   
>>   	switch ((u32)ctrl->type) {
>>   	case V4L2_CTRL_TYPE_INTEGER:
>> @@ -1435,7 +1449,11 @@ static int std_validate_elem(const struct v4l2_ctrl *ctrl, u32 idx,
>>   		return ROUND_TO_RANGE(ptr.p_u16[idx], u16, ctrl);
>>   	case V4L2_CTRL_TYPE_U32:
>>   		return ROUND_TO_RANGE(ptr.p_u32[idx], u32, ctrl);
>> -
>> +	case V4L2_CTRL_TYPE_S8:
>> +		tmp = ptr.p_s8[idx];
>> +		ROUND_TO_RANGE(tmp, s32, ctrl);
>> +		ptr.p_s8[idx] = (s8)tmp;
> 'ROUND_TO_RANGE(ptr.p_s8[idx], u8, ctrl)' should work just fine. No need for 'tmp'.
> The 'u8' type is used for an offset variable inside the macro that is always >= 0.
Got it, updated in v6
>> +		return 0;
> Add back the newline you removed above. It separates the 'integer' types from the
> boolean type.
Done
>>   	case V4L2_CTRL_TYPE_BOOLEAN:
>>   		ptr.p_s32[idx] = !!ptr.p_s32[idx];
>>   		return 0;
>> @@ -2030,6 +2048,9 @@ static struct v4l2_ctrl *v4l2_ctrl_new(struct v4l2_ctrl_handler *hdl,
>>   	case V4L2_CTRL_TYPE_U32:
>>   		elem_size = sizeof(u32);
>>   		break;
>> +	case V4L2_CTRL_TYPE_S8:
>> +		elem_size = sizeof(s8);
>> +		break;
>>   	case V4L2_CTRL_TYPE_MPEG2_SEQUENCE:
>>   		elem_size = sizeof(struct v4l2_ctrl_mpeg2_sequence);
>>   		break;
>> diff --git a/drivers/media/v4l2-core/v4l2-ctrls-defs.c b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
>> index e062f2088490470c42d6c579ff7675be454a29b0..8f895060799ea13443143edd398dfb97f4ba0085 100644
>> --- a/drivers/media/v4l2-core/v4l2-ctrls-defs.c
>> +++ b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
>> @@ -974,6 +974,8 @@ const char *v4l2_ctrl_get_name(u32 id)
>>   	case V4L2_CID_MPEG_VIDEO_AVERAGE_QP:			return "Average QP Value";
>>   	case V4L2_CID_FWHT_I_FRAME_QP:				return "FWHT I-Frame QP Value";
>>   	case V4L2_CID_FWHT_P_FRAME_QP:				return "FWHT P-Frame QP Value";
>> +	case V4L2_CID_MPEG_VIDEO_ROI_MB_DELTA_QP:		return "Encoder ROI MB Delta QP";
>> +	case V4L2_CID_MPEG_VIDEO_ROI_MB_SIZE:			return "Encoder ROI MB Size";
>>   
>>   	/* VPX controls */
>>   	case V4L2_CID_MPEG_VIDEO_VPX_NUM_PARTITIONS:		return "VPX Number of Partitions";
>> @@ -1622,6 +1624,14 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
>>   	case V4L2_CID_COLORIMETRY_HDR10_MASTERING_DISPLAY:
>>   		*type = V4L2_CTRL_TYPE_HDR10_MASTERING_DISPLAY;
>>   		break;
>> +	case V4L2_CID_MPEG_VIDEO_ROI_MB_DELTA_QP:
>> +		*type = V4L2_CTRL_TYPE_S8;
>> +		*flags |= V4L2_CTRL_FLAG_DYNAMIC_ARRAY;
>> +		break;
>> +	case V4L2_CID_MPEG_VIDEO_ROI_MB_SIZE:
>> +		*type = V4L2_CTRL_TYPE_U8;
>> +		*flags |= V4L2_CTRL_FLAG_READ_ONLY;
>> +		break;
>>   	default:
>>   		*type = V4L2_CTRL_TYPE_INTEGER;
>>   		break;
>> diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h
>> index a1806ddbc797efa52e83cd3f685ef70d5b5483d2..9a68a3555e349f1e55aa01af5c10f08201d62bae 100644
>> --- a/include/media/v4l2-ctrls.h
>> +++ b/include/media/v4l2-ctrls.h
>> @@ -27,6 +27,7 @@ struct video_device;
>>   
>>   /**
>>    * union v4l2_ctrl_ptr - A pointer to a control value.
>> + * @p_s8:			Pointer to a 8-bit signed value.
>>    * @p_s32:			Pointer to a 32-bit signed value.
>>    * @p_s64:			Pointer to a 64-bit signed value.
>>    * @p_u8:			Pointer to a 8-bit unsigned value.
>> @@ -61,10 +62,10 @@ struct video_device;
>>    * @p_const:			Pointer to a constant compound value.
>>    */
>>   union v4l2_ctrl_ptr {
>> +	s8 *p_s8;
>>   	s32 *p_s32;
>>   	s64 *p_s64;
>>   	u8 *p_u8;
>> -	s8 *p_s8;
>>   	u16 *p_u16;
>>   	u32 *p_u32;
>>   	char *p_char;
>>
> Regards,
>
> 	Hans