[linux-dvb] I2C Bus probing was Re: (temp. solution) modprobe mantis stalls/hangs/freezes (Twinhan VP-1034 and ivtv)

Hans Verkuil hverkuil at xs4all.nl
Sun Aug 26 19:03:33 CEST 2007

On Sunday 26 August 2007 18:45:44 Michael Krufky wrote:
> Manu Abraham wrote:
> > Michael Krufky wrote:
> > is
> >
> >>> Hans and Manu,
> >>> The mantis and ivtv module loaded ok with the following options
> >>> for saa7115 in /etc/modprobe.conf:
> >>> options saa7115 ignore=-1,0x25,-1,0x24,-1,0x21,-1,0x20
> >>
> >>                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> >>
> >> Just change the -1 to the i2c bus ID of the mantis device, to
> >> prevent saa7115 from probing on the mantis bus.  This way, it
> >> would not prevent successful attachment to the ivtv i2c bus, and
> >> you wouldn't have to do the hack described below.
> >
> > FYI,
> >
> > the bug is *not* with the mantis and *no* need to fix the mantis.
> > The bug comes from the extremely wrong concept followed (ie
> > probing) which i have mentioned numerous times, many places.
> Manu,
> You can go on and on about how probing is wrong -- I already agree
> with you in that respect.  Regardless, the saa7115 driver does this
> probe, and this will not change until after the new i2c methods are
> implemented in the video decoder i2c_client modules.
> I haven't looked at the Mantis code, but...  if you don't need to use
> any of the preexisting i2c client modules that attach via probing,
> then just remove I2C_CLASS_TV_DIGITAL from the i2c_adapter->class
> from within the Mantis driver.  This will prevent any probes from
> occurring on your device.

And I would appreciate comments on my approach to implement the 
new-style i2c API to existing i2c drivers. See the topic "[RFC] 
Converting wm8775.c to new-style I2C API" in the video4linux 

If there are no objections then it is very easy to convert an i2c 
driver. And once all i2c drivers used by e.g. ivtv can be used with the  
new-style i2c API (need a better name for that :-) ), then ivtv itself 
can be converted as well and probing will be (almost, some tuner 
addresses might need probing) a thing of the past. At least for ivtv, 
that is.

I'd be very glad when we can get this done since the current probing is 
playing havoc with some card configurations. This mantis issue isn't 
the first time it happened. I've had clashes with IR chips and audio 
chips before.



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