On 06/10/2015 09:04 AM, Ludovic Desroches wrote:
When having a controller which allows per pin muxing, declaring with
which groups a function can be used is a useless constraint since groups
are something virtual.
This isn't true.
Irrespective of whether a particular piece of pinmux HW can control the
mux function for each pin individually, or only in groups, it's quite
likely that each function can only be selected onto a subset of those
pins or groups. Requiring the pinctrl driver to inform the core which
set of pins/groups particular functions can be selected onto seems quite
reasonable.
In my opinion at least, for HW that can select the mux function at the
per-pin level, the only sensible set of groups is one group per pin with
each group containing a single pin. Any other use of groups is a
SW/user-level construct, and is something unrelated to why the pinctrl
subsystem supports groups. If we want to represent those groups in
pinctrl, there should be two separate sets of groups; one to represent
the actual HW capabilities, and one to represent the SW/user-level
convenience abstractions.
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