On 14.01.23 00:04, Philip Prindeville wrote:
Hello friends,
sorry for being so late, busy with totally different things ...
My read of Enrico's comments were that using ACPI information to map
the GPIO lines would break backward compatibility. This part of the
effort was dropped.
Yes, the big problem is inconsistent support in different firmware
versions in the field. Older version generally don't have any acpi
entries at all, later added it (but inconsitent and incomplete) and was
dropped again later (haven't checked whether they reintroduced it
again).
Obviously, we can't expect users in the field to upgrade firmware and
kernel in lockstep. So, we can only rely on this data for those boards
where we can be sure that all shipped firmware versions have proper
support (that really does it right). The problem also goes a bit deeper:
just adding the GPIOs isn't really enough, they need proper (and
consistent) names as well as mapping to the correct drivers (eg. LEDs).
Oh, BTW, don't arbitrarily change gpio line names (at least for the
already mainline-supported boards) - they're are used in the field.
(well, I'm not actually satisfied with direct gpio access or things
like modem reset lines, but haven't seen an actually fitting subsys
for those).
--mtx
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Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
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