Re: LinuxTV V3 vs. V4 API doc inconsistency, V4 probably wrong

[Mauro Carvalho Chehab <mchehab@s-opensource.com>]

Em Mon, 19 Jun 2017 16:58:40 +0200
Thierry Lelegard <thierry.lelegard@free.fr> escreveu:

> Hi,

First of all, there's no Linux DVB API v4. It was skipped, because there
was a proposal for a v4, with was never adopted.

> 
> There is an ambiguity in the LinuxTV documentation about the following 
> ioctl's:
> 
>     FE_SET_TONE, FE_SET_VOLTAGE, FE_DISEQC_SEND_BURST.
> 
> These ioctl's take an enum value as input. In the old V3 API, the 
> parameter
> is passed by value. In the S2API documentation, it is passed by 
> reference.
> Most sample programs (a bit old) use the "pass by value" method.
> 
> V3 documentation: https://www.linuxtv.org/docs/dvbapi/dvbapi.html
>     int ioctl(int fd, int request = FE_SET_TONE, fe_sec_tone_mode_t 
> tone);
>     int ioctl(int fd, int request = FE_SET_VOLTAGE, fe_sec_voltage_t 
> voltage);
>     int ioctl(int fd, int request = FE_DISEQC_SEND_BURST, 
> fe_sec_mini_cmd_t burst);
> 
> S2API documentation: 
> https://www.linuxtv.org/downloads/v4l-dvb-apis-new/uapi/dvb/frontend_fcalls.html
>     int ioctl(int fd, FE_SET_TONE, enum fe_sec_tone_mode *tone)
>     int ioctl(int fd, FE_SET_VOLTAGE, enum fe_sec_voltage *voltage)
>     int ioctl(int fd, FE_DISEQC_SEND_BURST, enum fe_sec_mini_cmd *tone)

Thanks for reviewing it! Yeah, the asterisks there are wrong.
The definitions should be, instead:

     int ioctl(int fd, FE_SET_TONE, enum fe_sec_tone_mode tone)
     int ioctl(int fd, FE_SET_VOLTAGE, enum fe_sec_voltage voltage)
     int ioctl(int fd, FE_DISEQC_SEND_BURST, enum fe_sec_mini_cmd tone)

As they're passing by value, not by reference[1].

Feel free to send us fix patches.

Thanks,
Mauro