[PATCH edid-decode 7/9] Print video format preference data block

[Arnaud Vrac]

On Fri, Jul 8, 2016 at 7:17 PM, walter harms <wharms at bfs.de> wrote:

>
>
> Am 08.07.2016 16:09, schrieb Arnaud Vrac:
> > From: Arnaud Vrac <avrac at freebox.fr>
> >
> > This only prints VIC codes, not DTD.
> > ---
> >  edid-decode.c | 31 +++++++++++++++++++++++++++++++
> >  1 file changed, 31 insertions(+)
> >
> > diff --git a/edid-decode.c b/edid-decode.c
> > index cd5a257..2e367b3 100644
> > --- a/edid-decode.c
> > +++ b/edid-decode.c
> > @@ -795,6 +795,36 @@ cea_y420vdb(unsigned char *x)
> >      cea_svd(x + 2, length - 1);
> >  }
> >
> > +static void
> > +cea_vfpdb(unsigned char *x)
> > +{
> > +    int length = x[0] & 0x1f;
> > +    int i;
> > +
> > +    for (i = 2; i <= length; i++)  {
> > +     unsigned char svr = x[i];
> > +
> > +     if ((svr > 0 && svr < 128) || (svr > 192 && svr < 254)) {
> > +         unsigned char vic;
> > +         const char *mode;
> > +         int index;
> > +
> > +         vic = svr;
> > +         index = vic - 1;
>
>
> why do you need vic ? i could be dropped for srv
> btw you are checking index and use vic.
>

This is just for clarity, I can remove it.


>
> > +
> > +         if (index < ARRAY_SIZE(edid_cea_modes))
> > +             mode = edid_cea_modes[vic];
> > +         else
> > +             mode = "Unknown mode";
> > +
> > +         printf("    VIC %02d %s\n", vic, mode);
> > +
> > +     } else if (svr > 128 && svr < 145) {
> > +         printf("    DTD number %02d\n", svr - 128);
> > +     }
> > +    }
> > +}
>
>
> when I see the ranges i am wondering  ...
>     [1-127] edid_cea_modes   [01-7F]
>     [129-144] DTD number     [81-91]
>     [193-253] edid_cea_modes [C0-FD]
>
> I would expect to see some pattern in the bits.
> Are you sure about the ranges ?
>

I'm sure about the ranges (they are in decimal in CEA 681-F), but I could
not find a pattern in the bits like I did in patch 2. So I preferred to
keep the same numbers that are in the spec.


>
> re,
>  wh
>
> > +
> >  static const char *edid_cea_hdmi_modes[] = {
> >      "3840x2160 at 30Hz",
> >      "3840x2160 at 25Hz",
> > @@ -1128,6 +1158,7 @@ cea_block(unsigned char *x)
> >                   break;
> >               case 0x0d:
> >                   printf("Video format preference data block\n");
> > +                 cea_vfpdb(x);
> >                   break;
> >               case 0x0e:
> >                   printf("YCbCr 4:2:0 video data block\n");


Thanks,

-- 
Arnaud
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