Re: [PATCH 21/66] rtl2830: implement own I2C locking

[Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>]

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> >Ok, this may eventually work ok for now, but a further change at the I2C
> >core could easily break it. So, we need to double check about such
> >patch with the I2C maintainer.
> >
> >Jean,
> >
> >Are you ok with such patch? If so, please ack.

Jean handed over I2C to me in late 2012 :)

> Basic problem here is that I2C-mux itself is controlled by same I2C device
> which implements I2C adapter for tuner.
> 
> Here is what connections looks like:
>  ___________         ____________         ____________
> |  USB IF   |       |   demod    |       |    tuner   |
> |-----------|       |------------|       |------------|
> |           |--I2C--|-----/ -----|--I2C--|            |
> |I2C master |       |  I2C mux   |       | I2C slave  |
> |___________|       |____________|       |____________|
> 
> 
> So when tuner is called via I2C, it needs recursively call same I2C adapter
> which is already locked. More elegant solution would be indeed nice.

So, AFAIU this is the same problem that I2C based mux devices have (like
drivers/i2c/muxes/i2c-mux-pca954x.c)? They also use the unlocked
transfers...


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