media: v4l: add I / P frame min max QP definitions

Add following V4L2 QP parameters for H.264:
* V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MIN_QP
* V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MAX_QP
* V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MIN_QP
* V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MAX_QP

These controls will limit QP range for intra and inter frame,
provide more manual control to improve video encode quality.
Signed-off-by: Fish Lin <linfish@google.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/media/uapi/v4l/ext-ctrls-codec.rst

@@ -1055,6 +1055,30 @@ enum v4l2_mpeg_video_h264_entropy_mode -
     Quantization parameter for an B frame for H264. Valid range: from 0
     to 51.
 
+``V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MIN_QP (integer)``
+    Minimum quantization parameter for the H264 I frame to limit I frame
+    quality to a range. Valid range: from 0 to 51. If
+    V4L2_CID_MPEG_VIDEO_H264_MIN_QP is also set, the quantization parameter
+    should be chosen to meet both requirements.
+
+``V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MAX_QP (integer)``
+    Maximum quantization parameter for the H264 I frame to limit I frame
+    quality to a range. Valid range: from 0 to 51. If
+    V4L2_CID_MPEG_VIDEO_H264_MAX_QP is also set, the quantization parameter
+    should be chosen to meet both requirements.
+
+``V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MIN_QP (integer)``
+    Minimum quantization parameter for the H264 P frame to limit P frame
+    quality to a range. Valid range: from 0 to 51. If
+    V4L2_CID_MPEG_VIDEO_H264_MIN_QP is also set, the quantization parameter
+    should be chosen to meet both requirements.
+
+``V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MAX_QP (integer)``
+    Maximum quantization parameter for the H264 P frame to limit P frame
+    quality to a range. Valid range: from 0 to 51. If
+    V4L2_CID_MPEG_VIDEO_H264_MAX_QP is also set, the quantization parameter
+    should be chosen to meet both requirements.
+
 ``V4L2_CID_MPEG_VIDEO_MPEG4_I_FRAME_QP (integer)``
     Quantization parameter for an I frame for MPEG4. Valid range: from 1
     to 31.

drivers/media/v4l2-core/v4l2-ctrls.c

@@ -828,6 +828,10 @@ const char *v4l2_ctrl_get_name(u32 id)
 	case V4L2_CID_MPEG_VIDEO_H264_CONSTRAINED_INTRA_PREDICTION:
 								return "H264 Constrained Intra Pred";
 	case V4L2_CID_MPEG_VIDEO_H264_CHROMA_QP_INDEX_OFFSET:	return "H264 Chroma QP Index Offset";
+	case V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MIN_QP:		return "H264 I-Frame Minimum QP Value";
+	case V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MAX_QP:		return "H264 I-Frame Maximum QP Value";
+	case V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MIN_QP:		return "H264 P-Frame Minimum QP Value";
+	case V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MAX_QP:		return "H264 P-Frame Maximum QP Value";
 	case V4L2_CID_MPEG_VIDEO_MPEG4_I_FRAME_QP:		return "MPEG4 I-Frame QP Value";
 	case V4L2_CID_MPEG_VIDEO_MPEG4_P_FRAME_QP:		return "MPEG4 P-Frame QP Value";
 	case V4L2_CID_MPEG_VIDEO_MPEG4_B_FRAME_QP:		return "MPEG4 B-Frame QP Value";

include/uapi/linux/v4l2-controls.h

@@ -539,6 +539,10 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type {
 #define V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_LAYER_QP	(V4L2_CID_MPEG_BASE+382)
 #define V4L2_CID_MPEG_VIDEO_H264_CONSTRAINED_INTRA_PREDICTION	(V4L2_CID_MPEG_BASE+383)
 #define V4L2_CID_MPEG_VIDEO_H264_CHROMA_QP_INDEX_OFFSET		(V4L2_CID_MPEG_BASE+384)
+#define V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MIN_QP	(V4L2_CID_MPEG_BASE+385)
+#define V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MAX_QP	(V4L2_CID_MPEG_BASE+386)
+#define V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MIN_QP	(V4L2_CID_MPEG_BASE+387)
+#define V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MAX_QP	(V4L2_CID_MPEG_BASE+388)
 #define V4L2_CID_MPEG_VIDEO_MPEG4_I_FRAME_QP	(V4L2_CID_MPEG_BASE+400)
 #define V4L2_CID_MPEG_VIDEO_MPEG4_P_FRAME_QP	(V4L2_CID_MPEG_BASE+401)
 #define V4L2_CID_MPEG_VIDEO_MPEG4_B_FRAME_QP	(V4L2_CID_MPEG_BASE+402)