[linux-dvb] bus control

Manu Abraham abraham.manu at gmail.com
Sun Jul 22 22:07:32 CEST 2007


Hi all,

On one of the devices that i am working upon, it has a bus control entity. ie

The device looks like this

The device consists of

1) a BUS Interface Unit
2) on this bus Interface unit (BIU) there is one single physical I2C bus
3) a built in MASTER demodulator


The I2C bus on the device is _not_ directly connected to any
peripherals such as demods and or tuners.

The bus goes to a control unit where the bus is split into 2 based on
a control word sent to the  Bus Control Unit (BCU)

The split out bus goes out like this

1) goes to the MASTER tuner for the built in demodulator
2) goes to a SLAVE demodulator, which has just one switchable I2C
output for the tuner

ie , the configuration looks like 2, 2 way switches cascaded together,
when the MASTER and SLAVE demodulators are cascaded.

Looking at the device and thinking a lot, i don't see how the control
can fit in as a part of the frontend at all, as the it has nothing to
do with the frontend, but just the BIU.

Some thought that i have, at present go like this

* register independant virtual buses for each device, on device
access, the relevant control word is appended to the BIU device
register.

* have one bus alone, but add a control for the bus such that the
control can be initiated from some place, but as i explained, this
control is not on the frontend/demodulator but on the Host controller.

I would like to hear comments people have on this, or better ideas if any.

Thanks,
Manu



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