[RFC PATCH 1/7] media: v4l2-ctrls: Add V4L2_CID_MEMORY_USAGE control

[ming . qian]

From: Ming Qian <ming.qian@xxxxxxxxxxx>

Add a new read-only control V4L2_CID_MEMORY_USAGE that allows
applications to query the total amount of memory currently used
by a device instance.

This control reports the memory consumption in bytes, including
internal buffers, intermediate processing data, and other
driver-managed allocations. Applications can use this information
for debugging, resource monitoring, or making informed decisions
about buffer allocation strategies.

Signed-off-by: Ming Qian <ming.qian@xxxxxxxxxxx>
---
 drivers/media/v4l2-core/v4l2-ctrls-defs.c | 8 ++++++++
 include/uapi/linux/v4l2-controls.h        | 4 +++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/media/v4l2-core/v4l2-ctrls-defs.c b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
index 551426c4cd01..053db78ff661 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls-defs.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
@@ -831,6 +831,7 @@ const char *v4l2_ctrl_get_name(u32 id)
 	case V4L2_CID_ALPHA_COMPONENT:		return "Alpha Component";
 	case V4L2_CID_COLORFX_CBCR:		return "Color Effects, CbCr";
 	case V4L2_CID_COLORFX_RGB:              return "Color Effects, RGB";
+	case V4L2_CID_MEMORY_USAGE:		return "Memory Usage";
 
 	/*
 	 * Codec controls
@@ -1476,6 +1477,13 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
 		*min = 0;
 		*max = 0xffff;
 		break;
+	case V4L2_CID_MEMORY_USAGE:
+		*type = V4L2_CTRL_TYPE_INTEGER64;
+		*flags |= V4L2_CTRL_FLAG_READ_ONLY;
+		*min = 0;
+		*max = S64_MAX;
+		*step = 1;
+		break;
 	case V4L2_CID_FLASH_FAULT:
 	case V4L2_CID_JPEG_ACTIVE_MARKER:
 	case V4L2_CID_3A_LOCK:
diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
index 68dd0c4e47b2..02c6f960d38e 100644
--- a/include/uapi/linux/v4l2-controls.h
+++ b/include/uapi/linux/v4l2-controls.h
@@ -110,8 +110,10 @@ enum v4l2_colorfx {
 #define V4L2_CID_COLORFX_CBCR			(V4L2_CID_BASE+42)
 #define V4L2_CID_COLORFX_RGB			(V4L2_CID_BASE+43)
 
+#define V4L2_CID_MEMORY_USAGE			(V4L2_CID_BASE+44)
+
 /* last CID + 1 */
-#define V4L2_CID_LASTP1                         (V4L2_CID_BASE+44)
+#define V4L2_CID_LASTP1                         (V4L2_CID_BASE+45)
 
 /* USER-class private control IDs */
 
-- 
2.53.0