The Qualcomm pinctrl driver has been violating the documented meaning
of PIN_CONFIG_INPUT_ENABLE. That documentation says:
Note that this does not affect the pin's ability to drive output.
...yet the Qualcomm driver's sole action when asked to "enable input"
on a pin is to disable its output.
The Qualcomm driver's implementation stems from the fact that
"output-disable" is a "new" property from 2017. It was introduced in
commit 425562429d ("pinctrl: generic: Add output-enable
property"). The "input-enable" handling in Qualcomm drivers is from
2015 introduced in commit 407f5e392f ("pinctrl: qcom: handle
input-enable pinconf property").
Let's change the Qualcomm driver to move us in the right direction. As
part of this:
1. We'll now support PIN_CONFIG_OUTPUT_ENABLE
2. We'll still support using PIN_CONFIG_INPUT_ENABLE to disable a
pin's output (in violation of the docs) with a big comment in the
code. This is needed because old device trees have "input-enable"
in them and, in some cases, people might need the old
behavior. While we could programmatically change all old device
trees, it doesn't really hurt to keep supporting the old behavior
and we're _supposed_ to try to be compatible with old device trees
anyway.
It can also be noted that the PIN_CONFIG_INPUT_ENABLE handling code
seems to have purposefully ignored its argument. That means that old
boards that had _either_ "input-disable" or "input-enable" in them
would have had the effect of disabling a pin's output. While we could
change this behavior, since we're only leaving the
PIN_CONFIG_INPUT_ENABLE there for backward compatibility we might as
well be fully backward compatible.
NOTE: despite the fact that we'll still support
PIN_CONFIG_INPUT_ENABLE for _setting_ config, we take it away from
msm_config_group_get(). This appears to be only used for populating
debugfs and fixing debugfs to "output enabled" where relevant instead
of "input enabled" makes more sense and has more truthiness.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230323102605.8.Id740ae6a993f9313b58add6b10f6a92795d510d4@changeid
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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