Em Mon, 6 May 2019 12:01:06 +0200
Hans Verkuil <hverkuil@xxxxxxxxx> escreveu:
> On 4/15/19 2:44 PM, Marco Felsch wrote:
> > Some connectors no matter if in- or output supports only a limited
> > range of tv norms. It doesn't matter if the hardware behind that
> > connector supports more than the listed formats since the users are
> > restriced by a label e.g. to plug only a camera into this connector
> > which uses the PAL format.
>
> For S-Video and Composite connectors there are really just two formats
> to consider: 50 and 60 Hz. I.e. there is no difference between PAL
> and SECAM. Only for tuners/modulators does this matter.
>
> So it is a good idea to add TVNORM_525_60, TVNORM_625_50 to tvnorms.h.
>
> In the various bindings examples I would recommend that you use
> TVNORM_525_60 or TVNORM_625_50 rather than e.g. PAL_M since that's what
> you would use in practice for Composite/S-Video.
Hans, that could be true for component video, but for S-Video and
Composite, you need to tell the demod how the color sub-carrier is
encoded, and what's its frequency, or otherwise it won't work.
There are plenty of equipments in Brazil that have both NTSC/M and
PAL/M (and a few with PAL/N') output. All those formats are 60Hz.
Colors are only decoded by tvp5150 and other demods if it is set
to the right color format (PAL or NTSC) and to the right line
frequency (60Hz) [1]. Also, some decoders are very sensitive to the
chroma sub-carrier frequency. That's the case of tvp5150.
[1] Or - when supported by the hardware - if the demod is set to
automatic mode.
Automatic mode usually doesn't work well with PAL/M and PAL/N'.
The problem is related to the sub-carrier frequency: both
PAL/N' (used only on Paraguay) and NTSC/M have the same
frequency; PAL/M has a close but different frequency for the
color sub-carrier.
Most decoders use the frequency of the chroma sub-carrier in
order to switch between NTSC/M nd PAL/M. So, auto-detection
usually fails with PAL/N', as such detectors understand it
as NTSC.
Worse than that, it is not uncommon to have pseudo-PAL-M devices
that were made for the US market, and received a conversion
to PAL, with envolves adding a small board with a NTSC->PAL converter.
As most TV sets used in this part of the world are designed to
work both with PAL/M and PAL/N' (by using a broader notch filter),
to make the hardware cheaper, lots of manufacturers just
change the modulation on encoders, while keeping the NTSC XTAL.
So, in practice, such devices, sold as "PAL/M" are actually PAL/N'.
A significant amount of old VCRs and DVD devices found in Brazil
are actually PAL/N'. The same applies to game consoles.
Btw, the main reason for having analog video streams here nowadays
is to copy old videos from VCRs and encode them digitally or to
record games from game consoles.
>
> Regards,
>
> Hans
>
> >
> > This patch adds the capability to describe such limitation within the
> > firmware. There are no format restrictions if the property isn't
> > present, so it's completely backward compatible.
> >
> > Signed-off-by: Marco Felsch <m.felsch@xxxxxxxxxxxxxx>
> > Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
> > ---
> > [1] https://patchwork.kernel.org/cover/10794703/
> >
> > v6:
> > - tvnorms.h: use tabs instead of spaces
> > - tvnorms.h: add TVNORM_PAL and TVNORM_SECAM
> > - tvnorms.h: drop rarely used TVNORM_ATSC_* norms
> >
> > v2-v4:
> > - nothing since the patch was squashed from series [1] into this
> > series.
> >
> > .../display/connector/analog-tv-connector.txt | 4 ++
> > include/dt-bindings/media/tvnorms.h | 56 +++++++++++++++++++
> > 2 files changed, 60 insertions(+)
> > create mode 100644 include/dt-bindings/media/tvnorms.h
> >
> > diff --git a/Documentation/devicetree/bindings/display/connector/analog-tv-connector.txt b/Documentation/devicetree/bindings/display/connector/analog-tv-connector.txt
> > index 0c0970c210ab..346f8937a0b7 100644
> > --- a/Documentation/devicetree/bindings/display/connector/analog-tv-connector.txt
> > +++ b/Documentation/devicetree/bindings/display/connector/analog-tv-connector.txt
> > @@ -6,6 +6,9 @@ Required properties:
> >
> > Optional properties:
> > - label: a symbolic name for the connector
> > +- tvnorms: limit the supported tv norms on a connector to the given ones else
> > + all tv norms are allowed. Possible video standards are defined in
> > + include/dt-bindings/media/tvnorms.h.
> >
> > Required nodes:
> > - Video port for TV input
> > @@ -16,6 +19,7 @@ Example
> > tv: connector {
> > compatible = "composite-video-connector";
> > label = "tv";
> > + tvnorms = <(TVNORM_PAL_M | TVNORM_NTSC_M)>;
> >
> > port {
> > tv_connector_in: endpoint {
> > diff --git a/include/dt-bindings/media/tvnorms.h b/include/dt-bindings/media/tvnorms.h
> > new file mode 100644
> > index 000000000000..058ab8414145
> > --- /dev/null
> > +++ b/include/dt-bindings/media/tvnorms.h
> > @@ -0,0 +1,56 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only or X11 */
> > +/*
> > + * Copyright 2019 Pengutronix, Marco Felsch <kernel@xxxxxxxxxxxxxx>
> > + */
> > +
> > +#ifndef _DT_BINDINGS_MEDIA_TVNORMS_H
> > +#define _DT_BINDINGS_MEDIA_TVNORMS_H
> > +
> > +/* one bit for each */
> > +#define TVNORM_PAL_B 0x00000001
> > +#define TVNORM_PAL_B1 0x00000002
> > +#define TVNORM_PAL_G 0x00000004
> > +#define TVNORM_PAL_H 0x00000008
> > +#define TVNORM_PAL_I 0x00000010
> > +#define TVNORM_PAL_D 0x00000020
> > +#define TVNORM_PAL_D1 0x00000040
> > +#define TVNORM_PAL_K 0x00000080
> > +
> > +#define TVNORM_PAL (TVNORM_PAL_B | \
> > + TVNORM_PAL_B1 | \
> > + TVNORM_PAL_G | \
> > + TVNORM_PAL_H | \
> > + TVNORM_PAL_I | \
> > + TVNORM_PAL_D | \
> > + TVNORM_PAL_D1 | \
> > + TVNORM_PAL_K)
> > +
> > +#define TVNORM_PAL_M 0x00000100
> > +#define TVNORM_PAL_N 0x00000200
> > +#define TVNORM_PAL_Nc 0x00000400
> > +#define TVNORM_PAL_60 0x00000800
> > +
> > +#define TVNORM_NTSC_M 0x00001000 /* BTSC */
> > +#define TVNORM_NTSC_M_JP 0x00002000 /* EIA-J */
> > +#define TVNORM_NTSC_443 0x00004000
> > +#define TVNORM_NTSC_M_KR 0x00008000 /* FM A2 */
> > +
> > +#define TVNORM_SECAM_B 0x00010000
> > +#define TVNORM_SECAM_D 0x00020000
> > +#define TVNORM_SECAM_G 0x00040000
> > +#define TVNORM_SECAM_H 0x00080000
> > +#define TVNORM_SECAM_K 0x00100000
> > +#define TVNORM_SECAM_K1 0x00200000
> > +#define TVNORM_SECAM_L 0x00400000
> > +#define TVNORM_SECAM_LC 0x00800000
> > +
> > +#define TVNORM_SECAM (TVNORM_SECAM_B | \
> > + TVNORM_SECAM_D | \
> > + TVNORM_SECAM_G | \
> > + TVNORM_SECAM_H | \
> > + TVNORM_SECAM_K | \
> > + TVNORM_SECAM_K1 | \
> > + TVNORM_SECAM_L | \
> > + TVNORM_SECAM_LC)
> > +
> > +#endif /* _DT_BINDINGS_MEDIA_TVNORMS_H */
Patch looks good to me.
Thanks,
Mauro
