[linux-dvb] Re: blocking FE_SET_FRONTEND ioctl in non-blocking mode

[Andrew de Quincey <adq_dvb@lidskialf.net>]

> I'd say it's a bug.
>
> Which frontend driver?
>
> Anyway, if it only happens once directly after open(), when initializing
> the frontend, I would say it's not worth fixing.

Its _probably_ a piece of extra code I added on purpose, forgetting about 
nonblocking mode. 

Without the code, the following was happening:

1) Application opens frontend device
2) Application calls FE_SETFRONTEND
3) Application creates a TS filter and starts reading it
4) The frontend tunes the device.

The problem is the device might be already tuned before step 1. In which case, 
the application gets some random transport stream data from the previous 
attempt, which was very confusing.

The code forces the thread doing the tuning to do:
1) Application opens frontend device
2) Application calls FE_SETFRONTEND
3) The frontend tunes the device.
4) Application creates a TS filter and starts reading it

However, looking back at it, I don't know if this is a good idea: (a) it has 
the nonblocking blocking issue, and (b) a multithreaded app might have 
different threads for tuning and for receiving data, in which case the 
getting-old-TS-data problem would still occur.

Anyone have an opinion on whether I should remove it?


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