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

[Mauro Carvalho Chehab <mchehab@osg.samsung.com>]

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Em Mon, 02 Feb 2015 21:33:24 +0100
Wolfram Sang <wsa@the-dreams.de> escreveu:

> 
> > >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 :)

Sorry for the mess... I mis-read MAINTAINERS.

> > 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...

If I understood your comment correct, you're ok with this approach,
right? I'll then merge the remaining of this 66-patch series.

If latter a better way to lock the I2C mux appears, we can reverse
this change.

Regards,
Mauro
> 

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