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

[Thierry Lelegard]

Hi,

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)

Also in: 
https://www.kernel.org/doc/html/v4.10/media/uapi/dvb/frontend_fcalls.html

Which one is correct? If both are correct and the API was changed (I 
doubt about it),
how can we know which one to use?

Normally, I would say that the most recent doc is right. However, all 
sample
codes use "by value". Moreover, if the most recent doc was right, then 
passing
by value should fail since the values are zero or close to zero and are 
not
valid addresses.

Thanks
-Thierry