Em Mon, 7 Jan 2013 22:25:47 -0200
Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> escreveu:
> The DVBv3 quality parameters are limited on several ways:
>
> - Doesn't provide any way to indicate the used measure,
> so userspace need to guess how to calculate the measure;
>
> - Only a limited set of stats are supported;
>
> - Can't be called in a way to require them to be filled
> all at once (atomic reads from the hardware), with may
> cause troubles on interpreting them on userspace;
>
> - On some OFDM delivery systems, the carriers can be
> independently modulated, having different properties.
> Currently, there's no way to report per-layer stats.
>
> To address the above issues, adding a new DVBv5-based stats
> API.
>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
>
...
> +struct dtv_stats {
> + __u8 scale; /* enum fecap_scale_params type */
> + union {
> + __u32 uvalue; /* for counters and relative scales */
> + __s32 svalue; /* for 0.1 dB measures */
32 bits for total bit count is not enough, as it can be truncated too
early (~1 seg on ISDB-T, ~0.5 seg on DVB-C). I think we need to use
64 bits here, and put at the API that the drivers should monotonically
increment.
As struct buffer inside struct dtv_property has 48 bytes, we can do such
change here without breaking userspace, as struct dtv_stats will have
37 bytes.
--
Cheers,
Mauro
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