[media] v4l2: use __u32 rather than enums in ioctl() structs
V4L2 uses the enum type in IOCTL arguments in IOCTLs that were defined until
the use of enum was considered less than ideal. Recently Rémi Denis-Courmont
brought up the issue by proposing a patch to convert the enums to unsigned:
<URL:http://www.spinics.net/lists/linux-media/msg46167.html>
This sparked a long discussion where another solution to the issue was
proposed: two sets of IOCTL structures, one with __u32 and the other with
enums, and conversion code between the two:
<URL:http://www.spinics.net/lists/linux-media/msg47168.html>
Both approaches implement a complete solution that resolves the problem. The
first one is simple but requires assuming enums and __u32 are the same in
size (so we won't break the ABI) while the second one is more complex and
less clean but does not require making that assumption.
The issue boils down to whether enums are fundamentally different from __u32
or not, and can the former be substituted by the latter. During the
discussion it was concluded that the __u32 has the same size as enums on all
archs Linux is supported: it has not been shown that replacing those enums
in IOCTL arguments would break neither source or binary compatibility. If no
such reason is found, just replacing the enums with __u32s is the way to go.
This is what this patch does. This patch is slightly different from Remi's
first RFC (link above): it uses __u32 instead of unsigned and also changes
the arguments of VIDIOC_G_PRIORITY and VIDIOC_S_PRIORITY.
Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>
Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index 5a09ac3..ace8ac0 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -292,10 +292,10 @@
__u32 width;
__u32 height;
__u32 pixelformat;
- enum v4l2_field field;
+ __u32 field; /* enum v4l2_field */
__u32 bytesperline; /* for padding, zero if unused */
__u32 sizeimage;
- enum v4l2_colorspace colorspace;
+ __u32 colorspace; /* enum v4l2_colorspace */
__u32 priv; /* private data, depends on pixelformat */
};
@@ -432,7 +432,7 @@
*/
struct v4l2_fmtdesc {
__u32 index; /* Format number */
- enum v4l2_buf_type type; /* buffer type */
+ __u32 type; /* enum v4l2_buf_type */
__u32 flags;
__u8 description[32]; /* Description string */
__u32 pixelformat; /* Format fourcc */
@@ -573,8 +573,8 @@
*/
struct v4l2_requestbuffers {
__u32 count;
- enum v4l2_buf_type type;
- enum v4l2_memory memory;
+ __u32 type; /* enum v4l2_buf_type */
+ __u32 memory; /* enum v4l2_memory */
__u32 reserved[2];
};
@@ -610,15 +610,17 @@
/**
* struct v4l2_buffer - video buffer info
* @index: id number of the buffer
- * @type: buffer type (type == *_MPLANE for multiplanar buffers)
+ * @type: enum v4l2_buf_type; buffer type (type == *_MPLANE for
+ * multiplanar buffers);
* @bytesused: number of bytes occupied by data in the buffer (payload);
* unused (set to 0) for multiplanar buffers
* @flags: buffer informational flags
- * @field: field order of the image in the buffer
+ * @field: enum v4l2_field; field order of the image in the buffer
* @timestamp: frame timestamp
* @timecode: frame timecode
* @sequence: sequence count of this frame
- * @memory: the method, in which the actual video data is passed
+ * @memory: enum v4l2_memory; the method, in which the actual video data is
+ * passed
* @offset: for non-multiplanar buffers with memory == V4L2_MEMORY_MMAP;
* offset from the start of the device memory for this plane,
* (or a "cookie" that should be passed to mmap() as offset)
@@ -636,16 +638,16 @@
*/
struct v4l2_buffer {
__u32 index;
- enum v4l2_buf_type type;
+ __u32 type;
__u32 bytesused;
__u32 flags;
- enum v4l2_field field;
+ __u32 field;
struct timeval timestamp;
struct v4l2_timecode timecode;
__u32 sequence;
/* memory location */
- enum v4l2_memory memory;
+ __u32 memory;
union {
__u32 offset;
unsigned long userptr;
@@ -708,7 +710,7 @@
struct v4l2_window {
struct v4l2_rect w;
- enum v4l2_field field;
+ __u32 field; /* enum v4l2_field */
__u32 chromakey;
struct v4l2_clip __user *clips;
__u32 clipcount;
@@ -745,14 +747,14 @@
* I N P U T I M A G E C R O P P I N G
*/
struct v4l2_cropcap {
- enum v4l2_buf_type type;
+ __u32 type; /* enum v4l2_buf_type */
struct v4l2_rect bounds;
struct v4l2_rect defrect;
struct v4l2_fract pixelaspect;
};
struct v4l2_crop {
- enum v4l2_buf_type type;
+ __u32 type; /* enum v4l2_buf_type */
struct v4l2_rect c;
};
@@ -1040,7 +1042,7 @@
__u8 name[32]; /* Label */
__u32 type; /* Type of input */
__u32 audioset; /* Associated audios (bitfield) */
- __u32 tuner; /* Associated tuner */
+ __u32 tuner; /* enum v4l2_tuner_type */
v4l2_std_id std;
__u32 status;
__u32 capabilities;
@@ -1157,7 +1159,7 @@
/* Used in the VIDIOC_QUERYCTRL ioctl for querying controls */
struct v4l2_queryctrl {
__u32 id;
- enum v4l2_ctrl_type type;
+ __u32 type; /* enum v4l2_ctrl_type */
__u8 name[32]; /* Whatever */
__s32 minimum; /* Note signedness */
__s32 maximum;
@@ -1792,7 +1794,7 @@
struct v4l2_tuner {
__u32 index;
__u8 name[32];
- enum v4l2_tuner_type type;
+ __u32 type; /* enum v4l2_tuner_type */
__u32 capability;
__u32 rangelow;
__u32 rangehigh;
@@ -1842,14 +1844,14 @@
struct v4l2_frequency {
__u32 tuner;
- enum v4l2_tuner_type type;
+ __u32 type; /* enum v4l2_tuner_type */
__u32 frequency;
__u32 reserved[8];
};
struct v4l2_hw_freq_seek {
__u32 tuner;
- enum v4l2_tuner_type type;
+ __u32 type; /* enum v4l2_tuner_type */
__u32 seek_upward;
__u32 wrap_around;
__u32 spacing;
@@ -2060,7 +2062,7 @@
(equals frame lines 313-336 for 625 line video
standards, 263-286 for 525 line standards) */
__u16 service_lines[2][24];
- enum v4l2_buf_type type;
+ __u32 type; /* enum v4l2_buf_type */
__u32 reserved[3]; /* must be 0 */
};
@@ -2141,8 +2143,8 @@
* @width: image width in pixels
* @height: image height in pixels
* @pixelformat: little endian four character code (fourcc)
- * @field: field order (for interlaced video)
- * @colorspace: supplemental to pixelformat
+ * @field: enum v4l2_field; field order (for interlaced video)
+ * @colorspace: enum v4l2_colorspace; supplemental to pixelformat
* @plane_fmt: per-plane information
* @num_planes: number of planes for this format
*/
@@ -2150,8 +2152,8 @@
__u32 width;
__u32 height;
__u32 pixelformat;
- enum v4l2_field field;
- enum v4l2_colorspace colorspace;
+ __u32 field;
+ __u32 colorspace;
struct v4l2_plane_pix_format plane_fmt[VIDEO_MAX_PLANES];
__u8 num_planes;
@@ -2160,7 +2162,7 @@
/**
* struct v4l2_format - stream data format
- * @type: type of the data stream
+ * @type: enum v4l2_buf_type; type of the data stream
* @pix: definition of an image format
* @pix_mp: definition of a multiplanar image format
* @win: definition of an overlaid image
@@ -2169,7 +2171,7 @@
* @raw_data: placeholder for future extensions and custom formats
*/
struct v4l2_format {
- enum v4l2_buf_type type;
+ __u32 type;
union {
struct v4l2_pix_format pix; /* V4L2_BUF_TYPE_VIDEO_CAPTURE */
struct v4l2_pix_format_mplane pix_mp; /* V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE */
@@ -2183,7 +2185,7 @@
/* Stream type-dependent parameters
*/
struct v4l2_streamparm {
- enum v4l2_buf_type type;
+ __u32 type; /* enum v4l2_buf_type */
union {
struct v4l2_captureparm capture;
struct v4l2_outputparm output;
@@ -2296,14 +2298,14 @@
* @index: on return, index of the first created buffer
* @count: entry: number of requested buffers,
* return: number of created buffers
- * @memory: buffer memory type
+ * @memory: enum v4l2_memory; buffer memory type
* @format: frame format, for which buffers are requested
* @reserved: future extensions
*/
struct v4l2_create_buffers {
__u32 index;
__u32 count;
- enum v4l2_memory memory;
+ __u32 memory;
struct v4l2_format format;
__u32 reserved[8];
};
@@ -2360,8 +2362,8 @@
#define VIDIOC_TRY_FMT _IOWR('V', 64, struct v4l2_format)
#define VIDIOC_ENUMAUDIO _IOWR('V', 65, struct v4l2_audio)
#define VIDIOC_ENUMAUDOUT _IOWR('V', 66, struct v4l2_audioout)
-#define VIDIOC_G_PRIORITY _IOR('V', 67, enum v4l2_priority)
-#define VIDIOC_S_PRIORITY _IOW('V', 68, enum v4l2_priority)
+#define VIDIOC_G_PRIORITY _IOR('V', 67, __u32) /* enum v4l2_priority */
+#define VIDIOC_S_PRIORITY _IOW('V', 68, __u32) /* enum v4l2_priority */
#define VIDIOC_G_SLICED_VBI_CAP _IOWR('V', 69, struct v4l2_sliced_vbi_cap)
#define VIDIOC_LOG_STATUS _IO('V', 70)
#define VIDIOC_G_EXT_CTRLS _IOWR('V', 71, struct v4l2_ext_controls)