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Re: [RFC v3 1/2] v4l: Do not use enums in IOCTL structs



On Wed May 2 2012 21:13:47 Sakari Ailus wrote:
> Replace enums in IOCTL structs by __u32. The size of enums is variable and
> thus problematic. Compatibility structs having exactly the same as original
> definition are provided for compatibility with old binaries with the
> required conversion code.

Does someone actually have hard proof that there really is a problem? You know,
demonstrate it with actual example code?

It's pretty horrible that you have to do all those conversions and that code
will be with us for years to come.

For most (if not all!) architectures sizeof(enum) == sizeof(u32), so there is
no need for any compat code for those.

Note that I don't question that using u32 is better than using enums, but I
really wonder if there is any need for all the conversions.

Regards,

	Hans

> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
> Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxx>
> Acked-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> ---
>  include/linux/videodev2.h  |   42 +++++-----
>  include/media/v4l2-ioctl.h |  209 ++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 230 insertions(+), 21 deletions(-)
> 
> diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
> index fed1d40..ec0928d 100644
> --- a/include/linux/videodev2.h
> +++ b/include/linux/videodev2.h
> @@ -292,10 +292,10 @@ struct v4l2_pix_format {
>  	__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_pix_format {
>   */
>  struct v4l2_fmtdesc {
>  	__u32		    index;             /* Format number      */
> -	enum v4l2_buf_type  type;              /* buffer type        */
> +	__u32		    type;	       /* buffer type (enum v4l2_buf_type) */
>  	__u32               flags;
>  	__u8		    description[32];   /* Description string */
>  	__u32		    pixelformat;       /* Format fourcc      */
> @@ -573,8 +573,8 @@ struct v4l2_jpegcompression {
>   */
>  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];
>  };
>  
> @@ -636,16 +636,16 @@ struct v4l2_plane {
>   */
>  struct v4l2_buffer {
>  	__u32			index;
> -	enum v4l2_buf_type      type;
> +	__u32			type;		/* enum v4l2_buf_type */
>  	__u32			bytesused;
>  	__u32			flags;
> -	enum v4l2_field		field;
> +	__u32			field;		/* enum v4l2_field */
>  	struct timeval		timestamp;
>  	struct v4l2_timecode	timecode;
>  	__u32			sequence;
>  
>  	/* memory location */
> -	enum v4l2_memory        memory;
> +	__u32		        memory;		/* enum v4l2_memory */
>  	union {
>  		__u32           offset;
>  		unsigned long   userptr;
> @@ -707,7 +707,7 @@ struct v4l2_clip {
>  
>  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;
> @@ -744,14 +744,14 @@ struct v4l2_outputparm {
>   *	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;
>  };
>  
> @@ -1156,7 +1156,7 @@ enum v4l2_ctrl_type {
>  /*  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;
> @@ -1791,7 +1791,7 @@ enum v4l2_jpeg_chroma_subsampling {
>  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;
> @@ -1841,14 +1841,14 @@ struct v4l2_modulator {
>  
>  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;
> @@ -2059,7 +2059,7 @@ struct v4l2_sliced_vbi_cap {
>  				 (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 */
>  };
>  
> @@ -2149,8 +2149,8 @@ struct v4l2_pix_format_mplane {
>  	__u32				width;
>  	__u32				height;
>  	__u32				pixelformat;
> -	enum v4l2_field			field;
> -	enum v4l2_colorspace		colorspace;
> +	__u32				field;		/* enum v4l2_field */
> +	__u32				colorspace;	/* enum v4l2_colorspace */
>  
>  	struct v4l2_plane_pix_format	plane_fmt[VIDEO_MAX_PLANES];
>  	__u8				num_planes;
> @@ -2168,7 +2168,7 @@ struct v4l2_pix_format_mplane {
>   * @raw_data:	placeholder for future extensions and custom formats
>   */
>  struct v4l2_format {
> -	enum v4l2_buf_type type;
> +	__u32	type;		/* enum v4l2_buf_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 */
> @@ -2182,7 +2182,7 @@ struct v4l2_format {
>  /*	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;
> @@ -2302,7 +2302,7 @@ struct v4l2_dbg_chip_ident {
>  struct v4l2_create_buffers {
>  	__u32			index;
>  	__u32			count;
> -	enum v4l2_memory        memory;
> +	__u32		        memory;		/* enum v4l2_memory */
>  	struct v4l2_format	format;
>  	__u32			reserved[8];
>  };
> diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
> index 3cb939c..77018d8 100644
> --- a/include/media/v4l2-ioctl.h
> +++ b/include/media/v4l2-ioctl.h
> @@ -333,4 +333,213 @@ extern long video_usercopy(struct file *file, unsigned int cmd,
>  extern long video_ioctl2(struct file *file,
>  			unsigned int cmd, unsigned long arg);
>  
> +/*
> + * Backward-compatible IOCTL's to be used by V4L2 core to work with the
> + * old ioctl's defined with "enum's" inside the structures
> + */
> +
> +#ifdef CONFIG_V4L2_COMPAT
> +
> +struct v4l2_pix_format_enum {
> +	__u32			width;
> +	__u32			height;
> +	__u32			pixelformat;
> +	enum v4l2_field		field;
> +	__u32			bytesperline;	/* for padding, zero if unused */
> +	__u32			sizeimage;
> +	enum v4l2_colorspace	colorspace;
> +	__u32			priv;		/* private data, depends on pixelformat */
> +};
> +
> +struct v4l2_fmtdesc_enum {
> +	__u32			index;             /* Format number      */
> +	enum v4l2_buf_type	type;              /* buffer type        */
> +	__u32			flags;
> +	__u8			description[32];   /* Description string */
> +	__u32			pixelformat;       /* Format fourcc      */
> +	__u32			reserved[4];
> +};
> +
> +struct v4l2_requestbuffers_enum {
> +	__u32			count;
> +	enum v4l2_buf_type	type;
> +	enum v4l2_memory	memory;
> +	__u32			reserved[2];
> +};
> +
> +struct v4l2_buffer_enum {
> +	__u32			index;
> +	enum v4l2_buf_type	type;
> +	__u32			bytesused;
> +	__u32			flags;
> +	enum v4l2_field		field;
> +	struct timeval		timestamp;
> +	struct v4l2_timecode	timecode;
> +	__u32			sequence;
> +
> +	/* memory location */
> +	enum v4l2_memory	memory;
> +	union {
> +		__u32		offset;
> +		unsigned long	userptr;
> +		struct v4l2_plane *planes;
> +	} m;
> +	__u32			length;
> +	__u32			reserved2;
> +	__u32			reserved;
> +};
> +
> +struct v4l2_framebuffer_enum {
> +	__u32			capability;
> +	__u32			flags;
> +/* FIXME: in theory we should pass something like PCI device + memory
> + * region + offset instead of some physical address */
> +	void			*base;
> +	struct v4l2_pix_format_enum fmt;
> +};
> +
> +struct v4l2_window_enum {
> +	struct v4l2_rect	w;
> +	enum v4l2_field		field;
> +	__u32			chromakey;
> +	struct v4l2_clip	__user *clips;
> +	__u32			clipcount;
> +	void			__user *bitmap;
> +	__u8			global_alpha;
> +};
> +
> +struct v4l2_cropcap_enum {
> +	enum v4l2_buf_type	type;
> +	struct v4l2_rect	bounds;
> +	struct v4l2_rect	defrect;
> +	struct v4l2_fract	pixelaspect;
> +};
> +
> +struct v4l2_crop_enum {
> +	enum v4l2_buf_type	type;
> +	struct v4l2_rect	c;
> +};
> +
> +struct v4l2_queryctrl_enum {
> +	__u32			id;
> +	enum v4l2_ctrl_type	type;
> +	__u8			name[32];	/* Whatever */
> +	__s32			minimum;	/* Note signedness */
> +	__s32			maximum;
> +	__s32			step;
> +	__s32			default_value;
> +	__u32			flags;
> +	__u32			reserved[2];
> +};
> +
> +struct v4l2_tuner_enum {
> +	__u32			index;
> +	__u8			name[32];
> +	enum v4l2_tuner_type	type;
> +	__u32			capability;
> +	__u32			rangelow;
> +	__u32			rangehigh;
> +	__u32			rxsubchans;
> +	__u32			audmode;
> +	__s32			signal;
> +	__s32			afc;
> +	__u32			reserved[4];
> +};
> +
> +struct v4l2_frequency_enum {
> +	__u32			tuner;
> +	enum v4l2_tuner_type	type;
> +	__u32			frequency;
> +	__u32			reserved[8];
> +};
> +
> +struct v4l2_hw_freq_seek_enum {
> +	__u32			tuner;
> +	enum v4l2_tuner_type	type;
> +	__u32			seek_upward;
> +	__u32			wrap_around;
> +	__u32			spacing;
> +	__u32			reserved[7];
> +};
> +
> +struct v4l2_sliced_vbi_cap_enum {
> +	__u16	service_set;
> +	/* service_lines[0][...] specifies lines 0-23 (1-23 used) of the first field
> +	   service_lines[1][...] specifies lines 0-23 (1-23 used) of the second field
> +				 (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	reserved[3];    /* must be 0 */
> +};
> +
> +struct v4l2_pix_format_mplane_enum {
> +	__u32				width;
> +	__u32				height;
> +	__u32				pixelformat;
> +	enum v4l2_field			field;
> +	enum v4l2_colorspace		colorspace;
> +
> +	struct v4l2_plane_pix_format	plane_fmt[VIDEO_MAX_PLANES];
> +	__u8				num_planes;
> +	__u8				reserved[11];
> +} __packed;
> +
> +struct v4l2_format_enum {
> +	enum v4l2_buf_type type;
> +	union {
> +		struct v4l2_pix_format_enum	pix;     /* V4L2_BUF_TYPE_VIDEO_CAPTURE */
> +		struct v4l2_pix_format_mplane_enum	pix_mp;  /* V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE */
> +		struct v4l2_window_enum		win;     /* V4L2_BUF_TYPE_VIDEO_OVERLAY */
> +		struct v4l2_vbi_format		vbi;     /* V4L2_BUF_TYPE_VBI_CAPTURE */
> +		struct v4l2_sliced_vbi_format	sliced;  /* V4L2_BUF_TYPE_SLICED_VBI_CAPTURE */
> +		__u8	raw_data[200];                   /* user-defined */
> +	} fmt;
> +};
> +
> +/*	Stream type-dependent parameters
> + */
> +struct v4l2_streamparm_enum {
> +	enum v4l2_buf_type type;
> +	union {
> +		struct v4l2_captureparm	capture;
> +		struct v4l2_outputparm	output;
> +		__u8	raw_data[200];  /* user-defined */
> +	} parm;
> +};
> +
> +struct v4l2_create_buffers_enum {
> +	__u32			index;
> +	__u32			count;
> +	enum v4l2_memory	memory;
> +	struct v4l2_format_enum	format;
> +	__u32			reserved[8];
> +};
> +
> +#define VIDIOC_ENUM_FMT_ENUM		_IOWR('V',  2, struct v4l2_fmtdesc_enum)
> +#define VIDIOC_G_FMT_ENUM		_IOWR('V',  4, struct v4l2_format_enum)
> +#define VIDIOC_S_FMT_ENUM		_IOWR('V',  5, struct v4l2_format_enum)
> +#define VIDIOC_REQBUFS_ENUM		_IOWR('V',  8, struct v4l2_requestbuffers_enum)
> +#define VIDIOC_QUERYBUF_ENUM		_IOWR('V',  9, struct v4l2_buffer_enum)
> +#define VIDIOC_G_FBUF_ENUM		_IOR('V', 10, struct v4l2_framebuffer_enum)
> +#define VIDIOC_S_FBUF_ENUM		_IOW('V', 11, struct v4l2_framebuffer_enum)
> +#define VIDIOC_QBUF_ENUM		_IOWR('V', 15, struct v4l2_buffer_enum)
> +#define VIDIOC_DQBUF_ENUM		_IOWR('V', 17, struct v4l2_buffer_enum)
> +#define VIDIOC_G_PARM_ENUM		_IOWR('V', 21, struct v4l2_streamparm_enum)
> +#define VIDIOC_S_PARM_ENUM		_IOWR('V', 22, struct v4l2_streamparm_enum)
> +#define VIDIOC_G_TUNER_ENUM		_IOWR('V', 29, struct v4l2_tuner_enum)
> +#define VIDIOC_S_TUNER_ENUM		_IOW('V', 30, struct v4l2_tuner_enum)
> +#define VIDIOC_QUERYCTRL_ENUM		_IOWR('V', 36, struct v4l2_queryctrl_enum)
> +#define VIDIOC_G_FREQUENCY_ENUM		_IOWR('V', 56, struct v4l2_frequency_enum)
> +#define VIDIOC_S_FREQUENCY_ENUM		_IOW('V', 57, struct v4l2_frequency_enum)
> +#define VIDIOC_CROPCAP_ENUM		_IOWR('V', 58, struct v4l2_cropcap_enum)
> +#define VIDIOC_G_CROP_ENUM		_IOWR('V', 59, struct v4l2_crop_enum)
> +#define VIDIOC_S_CROP_ENUM		_IOW('V', 60, struct v4l2_crop_enum)
> +#define VIDIOC_TRY_FMT_ENUM		_IOWR('V', 64, struct v4l2_format_enum)
> +#define VIDIOC_G_SLICED_VBI_CAP_ENUM	_IOWR('V', 69, struct v4l2_sliced_vbi_cap_enum)
> +#define VIDIOC_S_HW_FREQ_SEEK_ENUM	_IOW('V', 82, struct v4l2_hw_freq_seek_enum)
> +#define VIDIOC_CREATE_BUFS_ENUM		_IOWR('V', 92, struct v4l2_create_buffers_enum)
> +#define VIDIOC_PREPARE_BUF_ENUM		_IOWR('V', 93, struct v4l2_buffer_enum)
> +#endif /* CONFIG_V4L2_COMPAT */
> +
>  #endif /* _V4L2_IOCTL_H */
> 
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