"cell-index" vs. "index" vs. no index in I2C device nodes

Josh Boyer jwboyer at linux.vnet.ibm.com
Fri Jun 6 04:56:25 EST 2008


On Thu, 5 Jun 2008 12:46:39 -0600
"Grant Likely" <grant.likely at secretlab.ca> wrote:

> > (And I'm talking about I2C, not DMA.  I don't care about DMA because
> > this conversation will go off into the weeds if we start talking about
> > cell-index and every possible device out there.)
> 
> I need to disagree here.  Behavior should never be dependent on device
> tree order.  It should be absolutely fine for devices to be probed in
> a different order and different bus ids to be assigned.

Meh.  I'll begrudgingly agree.

> In Timur's case, it is absolutely appropriate to use cell-index and/or
> a phandle to make sure it gets the correct DMA registers (which is
> what cell-index is intended to solve).  It is not appropriate to
> depend on that same number to also be the logical i2c bus number.

Hence "index" would be a better fit for the latter then, yes?

josh



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