[linux-dvb] Re: NEWSTRUCT questions

[Johannes Stezenbach <js@convergence.de>]

Hi,

On Wed, Oct 23, 2002 at 12:01:48PM +0200, Florian Schirmer wrote:
> 
> we're currently porting all our D-BOX2 driver to the NEWSTRUCT API's and 
> running into major problems with the new i2c layer.

NEWSTRUCT is history...
We were trying to push the DVB API/framework and our favourite driver
into the 2.5 kernel, and cleaned up some type naming issues.

See http://linuxtv.org/mailinglists/linux-dvb/2002/10-2002/msg00183.html
The script attached there can be used to help porting your sources to the
new API.

> The i2c layer works pretty well as long as the i2c adapter is part of the dvb 
> adapter. On our STB there are three i2c controller. Two of them are not part 
> of the dvb adapter and so not under the control of the dvb i2c layer.
> 
> The frontends of our STB are attached to one of the "external" i2c adapters. 
> Because of this we are running into problems when attaching the frontends to 
> the dvb adapter.
> 
> Currently i'm not aware of any possible workaround for this situation. We've 
> tried to register a dummy i2c bus at the dvb i2c layer. Then fe's can 
> properly attach to the dvb adapter. But we have to deal with the i2c messages 
> ourself. And there is no way to enumerate the availible i2c busses on the 
> linux i2c api. So we dont can't send the messages inside the dummy i2c bus 
> xfer_msg proc.
> 
> To work around this problem again we have to register the frontend to the 
> linux i2c layer too, as soon it is attached to our dummy dvb i2c bus.
> 
> This is a very ugly hack. Maybe there is a smarter solution to this kind of 
> problem. It would be nice if someone can elaborate on this subject.

Well, the Linux I2C subsystem has the problem that when you register
a frontend driver, it will probe for the frontend on all known I2C
busses. This causes some long timeouts when you have e.g. a Matrox
graphics card and enabled Matrox I2C support.

The DVB driver should be able to tell the I2C subsystem to probe for
frontends only on a specific I2C bus. (The frontend drivers are
the same for all systems, so they know nothing about the busses.)

Maybe Holger knows a solution?


> Another simple question: 
> 
> FE_CAN_FEC_x_y does it tell the api the fe can do fec x/y or does it tell the 
> fe can be forced to operate in fec x/y mode. We've a fe which is able to do 
> fec x/y but can only operate in auto fec mode. So do we need to set 
> FE_CAN_FEC_x_y AND FE_CAN_FEC_AUTO or just FE_CAN_FEC_AUTO?

Both, so that an application can see whether the frontend can
lock on signals with e.g. FEC_8_9 or not.


Regards,
Johannes


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