On Tuesday, February 28, 2012 11:54:54 Mauro Carvalho Chehab wrote:
> Em 03-02-2012 08:06, Hans Verkuil escreveu:
> > From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
> >
> > These new ioctls make it possible for the dv_timings API to replace
> > the dv_preset API eventually.
> >
> > Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
> > ---
> > include/linux/videodev2.h | 110 ++++++++++++++++++++++++++++++++++++++++----
> > 1 files changed, 100 insertions(+), 10 deletions(-)
> >
> > diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
> > index 0db0503..e59cd02 100644
> > --- a/include/linux/videodev2.h
> > +++ b/include/linux/videodev2.h
> > @@ -987,28 +987,42 @@ struct v4l2_dv_enum_preset {
> > */
> >
> > /* BT.656/BT.1120 timing data */
> > +
> > +/*
> > + * A note regarding vertical interlaced timings: height refers to the total
> > + * height of the frame (= two fields). The blanking timings refer
> > + * to the blanking of each field. So the height of the active frame is
> > + * calculated as follows:
> > + *
> > + * act_height = height - vfrontporch - vsync - vbackporch -
> > + * il_vfrontporch - il_vsync - il_vbackporch
> > + *
> > + * The active height of each field is act_height / 2.
> > + */
> > struct v4l2_bt_timings {
> > - __u32 width; /* width in pixels */
> > - __u32 height; /* height in lines */
> > + __u32 width; /* total frame width in pixels */
> > + __u32 height; /* total frame height in lines */
> > __u32 interlaced; /* Interlaced or progressive */
> > __u32 polarities; /* Positive or negative polarity */
> > __u64 pixelclock; /* Pixel clock in HZ. Ex. 74.25MHz->74250000 */
> > - __u32 hfrontporch; /* Horizpontal front porch in pixels */
> > + __u32 hfrontporch; /* Horizontal front porch in pixels */
> > __u32 hsync; /* Horizontal Sync length in pixels */
> > __u32 hbackporch; /* Horizontal back porch in pixels */
> > __u32 vfrontporch; /* Vertical front porch in pixels */
> > __u32 vsync; /* Vertical Sync length in lines */
> > __u32 vbackporch; /* Vertical back porch in lines */
> > - __u32 il_vfrontporch; /* Vertical front porch for bottom field of
> > - * interlaced field formats
> > + __u32 il_vfrontporch; /* Vertical front porch for the even field
> > + * (aka field 2) of interlaced field formats
> > */
> > - __u32 il_vsync; /* Vertical sync length for bottom field of
> > - * interlaced field formats
> > + __u32 il_vsync; /* Vertical sync length for the even field
> > + * (aka field 2) of interlaced field formats
> > */
> > - __u32 il_vbackporch; /* Vertical back porch for bottom field of
> > - * interlaced field formats
> > + __u32 il_vbackporch; /* Vertical back porch for the even field
> > + * (aka field 2) of interlaced field formats
> > */
> > - __u32 reserved[16];
> > + __u32 standards; /* Standards the timing belongs to */
> > + __u32 flags; /* Flags */
> > + __u32 reserved[14];
> > } __attribute__ ((packed));
> >
> > /* Interlaced or progressive format */
> > @@ -1019,6 +1033,37 @@ struct v4l2_bt_timings {
> > #define V4L2_DV_VSYNC_POS_POL 0x00000001
> > #define V4L2_DV_HSYNC_POS_POL 0x00000002
> >
> > +/* Timings standards */
> > +#define V4L2_DV_BT_STD_CEA861 (1 << 0) /* CEA-861 Digital TV Profile */
> > +#define V4L2_DV_BT_STD_DMT (1 << 1) /* VESA Discrete Monitor Timings */
> > +#define V4L2_DV_BT_STD_CVT (1 << 2) /* VESA Coordinated Video Timings */
> > +#define V4L2_DV_BT_STD_GTF (1 << 3) /* VESA Generalized Timings Formula */
> > +
> > +/* Flags */
> > +
> > +/* CVT/GTF specific: timing uses reduced blanking (CVT) or the 'Secondary
> > + GTF' curve (GTF). In both cases the horizontal and/or vertical blanking
> > + intervals are reduced, allowing a higher resolution over the same
> > + bandwidth. This is a read-only flag. */
> > +#define V4L2_DV_FL_REDUCED_BLANKING (1 << 0)
>
> > +/* CEA-861 specific: set for CEA-861 formats with a framerate of a multiple
> > + of six. These formats can be optionally played at 1 / 1.001 speed to
> > + be compatible with the normal NTSC framerate of 29.97 frames per second.
> > + This is a read-only flag. */
> > +#define V4L2_DV_FL_NTSC_COMPATIBLE (1 << 1)
> > +/* CEA-861 specific: only valid for video transmitters, the flag is cleared
> > + by receivers.
> > + If the framerate of the format is a multiple of six, then the pixelclock
> > + used to set up the transmitter is divided by 1.001 to make it compatible
> > + with NTSC framerates. Otherwise this flag is cleared. If the transmitter
> > + can't generate such frequencies, then the flag will also be cleared. */
> > +#define V4L2_DV_FL_DIVIDE_CLOCK_BY_1_001 (1 << 2)
>
> The two above have a conceptual problem: NTSC has nothing to do with the frequency.
>
> While, in practice, NTSC is only used on Countries with 60Hz power supply, and a
> 1000/1001 shift is used there, to avoid flicker with the light bulbs, the
> standard doesn't mean a 29.97 Hz frame rate.
>
> If you take a look at CEA-861, it doesn't mention there NTSC (well, except for a
> reference for the existing standards), to avoid such conceptual issue.
>
> Besides that, PAL/M (and PAL/60) also uses a 29.97 Hz frame rate, in order to avoid
> flicker.
>
> So, please don't call the flag as "NTSC_COMPATIBLE", and please fix the comments
> to either not mention NTSC, or to use something more generic, like replacing:
>
> "...be compatible with the normal NTSC framerateof 29.97 frames per second."
> with
> "...be compatible with 60Hz based standards that use a framerate of 29.97
> frames per second, like NTSC and PAL/M."
I'll try and find a more neutral term. I'm not satisfied with the name either.
>
> > +/* Specific to interlaced formats: if set, then field 1 is really one half-line
> > + longer and field 2 is really one half-line shorter, so each field has
> > + exactly the same number of half-lines. Whether half-lines can be detected
> > + or used depends on the hardware. */
> > +#define V4L2_DV_FL_HALF_LINE (1 << 0)
> > +
> >
> > /* DV timings */
> > struct v4l2_dv_timings {
> > @@ -1032,6 +1077,47 @@ struct v4l2_dv_timings {
> > /* Values for the type field */
> > #define V4L2_DV_BT_656_1120 0 /* BT.656/1120 timing type */
> >
> > +
> > +/* DV timings enumeration */
> > +struct v4l2_enum_dv_timings {
> > + __u32 index;
> > + __u32 reserved[3];
> > + struct v4l2_dv_timings timings;
> > +};
> > +
> > +/* BT.656/BT.1120 timing capabilities */
> > +struct v4l2_bt_timings_cap {
> > + __u32 min_width; /* width in pixels */
> > + __u32 max_width; /* width in pixels */
> > + __u32 min_height; /* height in lines */
> > + __u32 max_height; /* height in lines */
> > + __u64 min_pixelclock; /* Pixel clock in HZ. Ex. 74.25MHz->74250000 */
> > + __u64 max_pixelclock; /* Pixel clock in HZ. Ex. 74.25MHz->74250000 */
> > + __u32 standards; /* Supported standards */
> > + __u32 capabilities; /* See below */
> > + __u32 reserved[16];
> > +} __attribute__ ((packed));
>
> Hmm... why to define a new struct here, instead of just use struct v4l2_bt_timings ?
Perhaps there is some misunderstanding here? Struct v4l2_bt_timings defines the
timings of a particular format. Struct v4l2_bt_timings_cap defines the range of
timings that the hardware is capable of. The fields are quite different between
the two.
>
> > +
> > +/* Supports interlaced formats */
> > +#define V4L2_DV_BT_CAP_INTERLACED (1 << 0)
> > +/* Supports progressive formats */
> > +#define V4L2_DV_BT_CAP_PROGRESSIVE (1 << 1)
> > +/* Supports CVT/GTF reduced blanking */
> > +#define V4L2_DV_BT_CAP_REDUCED_BLANKING (1 << 2)
> > +/* Supports custom formats */
> > +#define V4L2_DV_BT_CAP_CUSTOM (1 << 3)
> > +
> > +/* DV timings capabilities */
> > +struct v4l2_dv_timings_cap {
> > + __u32 type;
>
> What are the posible values for type?
Same as the type of v4l2_dv_timings. I'll clarify this.
> Btw, it is a good idea to use kernel-doc-nano to describe the structures:
>
> /**
> * struct v4l2_dv_timings_cap - DV timings capabilities
> * @type: some description
> ...
> */
>
> As it documents better what is defined there.
Certainly.
> > + __u32 reserved[3];
> > + union {
> > + struct v4l2_bt_timings_cap bt;
> > + __u32 raw_data[32];
> > + };
> > +};
> > +
> > +
> > /*
> > * V I D E O I N P U T S
> > */
> > @@ -2318,6 +2404,10 @@ struct v4l2_create_buffers {
> > #define VIDIOC_G_SELECTION _IOWR('V', 94, struct v4l2_selection)
> > #define VIDIOC_S_SELECTION _IOWR('V', 95, struct v4l2_selection)
> >
> > +#define VIDIOC_ENUM_DV_TIMINGS _IOWR('V', 96, struct v4l2_enum_dv_timings)
> > +#define VIDIOC_QUERY_DV_TIMINGS _IOR('V', 97, struct v4l2_dv_timings)
> > +#define VIDIOC_DV_TIMINGS_CAP _IOWR('V', 98, struct v4l2_dv_timings_cap)
> > +
> > /* Reminder: when adding new ioctls please add support for them to
> > drivers/media/video/v4l2-compat-ioctl32.c as well! */
> >
>
Thanks for reviewing this!
Regards,
Hans
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