[PATCH v4] 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

[Fish Lin]

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@xxxxxxxxxx>
---
Changelog since v3:
- Put document in ext-ctrls-codec.rst instead of extended-controls.rst
  (which was previous version).

Changelog since v2:
- Add interaction with V4L2_CID_MPEG_VIDEO_H264_MIN/MAX_QP
  description in the document.

Changelog since v1:
- Add description in document.

 .../media/uapi/v4l/ext-ctrls-codec.rst        | 24 +++++++++++++++++++
 drivers/media/v4l2-core/v4l2-ctrls.c          |  4 ++++
 include/uapi/linux/v4l2-controls.h            |  6 +++++
 3 files changed, 34 insertions(+)

diff --git a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
index c97fb7923be5..de60b2e788eb 100644
--- a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
+++ b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
@@ -1048,6 +1048,30 @@ 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 H264 I frame, to limit I frame
+    quality in 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 H264 I frame, to limit I frame
+    quality in 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 H264 P frame, to limit P frame
+    quality in 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 H264 P frame, to limit P frame
+    quality in 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.
diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
index b79d3bbd8350..115fb8debe23 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls.c
+++ b/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";
diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
index 06479f2fb3ae..4421baa84177 100644
--- a/include/uapi/linux/v4l2-controls.h
+++ b/include/uapi/linux/v4l2-controls.h
@@ -535,6 +535,12 @@ 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+390)
+#define V4L2_CID_MPEG_VIDEO_H264_I_FRAME_MAX_QP	(V4L2_CID_MPEG_BASE+391)
+#define V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MIN_QP	(V4L2_CID_MPEG_BASE+392)
+#define V4L2_CID_MPEG_VIDEO_H264_P_FRAME_MAX_QP	(V4L2_CID_MPEG_BASE+393)
+
 #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)
-- 
2.21.0.360.g471c308f928-goog