[linux-dvb] Re: INVERSION_AUTO used by latest scan breaks grundig_29504-401fe

[Holger Waechtler <holger@convergence.de>]

Hi Jon,

Jon Burgess wrote:
> The latest scan code defaults to using the "INVERSION_AUTO" parameter of 
> the frontend. Unfortunately this breaks my Nova-T card since the grundig 
> 401 frontend does not support this mode.
>
> This reveals a couple of problems:
> - The scan and vdr-1.2.0 applications both ignore the frontend flag for 
> "FE_CAN_INVERSION_AUTO" and will ask for this mode even if the frontend 
> doesn't claim to support it.
>
> - The grundig_29504-401 apply_frontend_param() aborts and returns 
> "-EINVAL" if the application tries to set INVERSION_AUTO, but the ioctl 
> code which calls this function just ignores the return code.
definitely a bug, but maybe it's better to implement 
software-auto-inversion as you can see for example in the ves1820 and 
stv0299 driver.

Don't know if we should force the application to autoprobe the inversion 
setting instead of implementing this in all drivers, in the ves1820 and 
stv0299 driver there was a definite need to do it because there are 
frontends out there with swapped I/Q pins where we simply don't know the 
'real' inversion.


> The result is a bit of a mess. Ideally all three bits of code need to 
> change.
>
> Does anyone else want to fix the frontend code and scan application or 
> should I try to fix it myself?
I don't have a L64781 based card here right now, so you get probably 
faster results when you do it on your own...
:)

Holger



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