On 02/03/2015 07:53 PM, Mauro Carvalho Chehab wrote:
Em Mon, 02 Feb 2015 21:33:24 +0100
Wolfram Sang <wsa@xxxxxxxxxxxxx> 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.
More I am worried about next patch in a serie, which converts all that
to regmap API... Same recursive mux register access comes to problem
there, which I work-arounded by defining own I2C IO... And in that case
I used i2c_lock_adapter/i2c_unlock_adapter so adapter is locked properly.
[PATCH 22/66] rtl2830: convert to regmap API
http://www.spinics.net/lists/linux-media/msg84969.html
regards
Antti
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http://palosaari.fi/
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