[U-Boot] [PATCH] serial: ns16550: Add register shift variable

[Wolfgang Denk]

Dear Felix,

In message <1b0d33fa-adfb-9825-5ae8-8bded1678c0c at ltec.ch> you wrote:
>
> >> This needs to be rewritten.
> > 
> > To try and help clarify, the property in question means "quantity to
> > shift the register offsets by."  It should be clear in our Kconfig help
> > entry as well that this is what we're looking for.
> > 
> Thanks for this! The help text will be fixed in v2.

None of the places I could find in the Linux
Documentation/devicetree/bindings directory actually explains what
"shift the register offsets" means.   Only the code reveals that
this means a LEFT shift of the register address (offset).

At least one place in Linux interprets <reg-shift> differently; here
it operates on the _data_ (instead there they use <reg-spacing>):

"devicetree/bindings/ipmi/ipmi-smic.txt":

- reg-shift - The amount to shift the registers to the right to get the data
        into bit zero.

(see ipmi_si_mem_io.c


So can we please add an explanation what _exactly_ this means?

Thanks.


Wolfgang Denk

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