[linux-dvb] Re: cinergyT2: which kernel/usb module to use?

[Holger Waechtler <holger@qanu.de>]

Hi Stefan,

Stefan Lucke wrote:

> On Freitag, 26. November 2004 14:23, Klaus Schmidinger wrote:
>  
> > Holger Waechtler wrote:
> >    
> > > Johannes Stezenbach wrote:
> > >
> > >      
> > > > My cinergyT2 works fine here (2.6.10-rc2 + current dvb-kernel CVS).
> > > >
> > > > There's a bug in the cinergyT2 frontend code when prevents it from
> > > > working with VDR, though (no frontend events).
> > > >
> > > >
> > > >        
> > > the FE_GET_EVENT ioctl was simply not implemented (I already rendered it 
> > > obsolete in my mind, since GET_STATUS and GET_FRONTEND provide the same 
> > > functionality...).
> > > please try again,
> > >
> > > Holger
> > >      
> > I was under the impression that FE_GET_EVENT was the correct way
> > for an application to determine whether there is a transponder lock.
> > If this isn't the case, what exactly _is_ the right way to do this?
> >    
> Sorry when I stumble in a discussion where I have no deep knowledge.
> But code like:
>
> while (ioctl (something) == 0)
> 	;
>
> is to my opinion boguous.
>
> man ioctl:
> RETURN VALUE
>       Usually, on success zero is returned.  A  few  ioctls  use
>       the  return value as an output parameter and return a non­
>       negative value on success.  On error, -1 is returned,  and
>       errno is set appropriately.
>
> but a loop like:
>
> bool cDvbTuner::GetFrontendEvent(dvb_frontend_event &Event, int TimeoutMs)
> {
>  if (TimeoutMs) {
>     struct pollfd pfd;
>     pfd.fd = fd_frontend;
>     pfd.events = POLLIN | POLLPRI;
>     do {
>        int stat = poll(&pfd, 1, TimeoutMs);
>        if (stat == 1)
>           break;
>        if (stat < 0) {
>           if (errno == EINTR)
>              continue;
>           esyslog("ERROR: frontend %d poll failed: %m", cardIndex);
>           }
>        return false;
>        } while (0);
>     }
>  do {
>     int stat = ioctl(fd_frontend, FE_GET_EVENT, &Event);
>     if (stat == 0)
>        return true; //stefan lucke: ioctl is successful, so return ! the only way to break this loop.
>     if (stat < 0) {
>        if (errno == EINTR)
>           continue;
>        }
>     } while (0);
>  
the problem is here: You should exit your loop in any case for all 
errno's != EINTR and silently return a non-zero error value since a 
missing implementation of this ioctl is usually uncritical.

Holger