Re: [PATCH v3 3/7] arm: dts: dt-bindings: Add Renesas RZ pinctrl header

On Wed, Mar 29, 2017 at 4:55 PM, Chris Brandt [off-list ref] wrote:

On Wednesday, March 29, 2017, Linus Walleij wrote:

quoted

On Fri, Mar 24, 2017 at 4:22 PM, Jacopo Mondi [off-list ref]
wrote:

quoted

Add dt-bindings for Renesas r7s72100 pin controller header file.

Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>

quoted

+/*
+ * Pin is bi-directional.
+ * An alternate function that needs both input/output functionalities
+shall
+ * be configured as bidirectional.
+ * Eg. SDA/SCL pins of an I2c interface.
+ */
+#define BI_DIR                 (1 << 3)

Any specific reason why this should not simply be added to
include/linux/pinctrl/pinconf-generic.h
as PIN_CONFIG_BIDIRECTIONAL and parsed in drivers/pinctrl/pinconf-
generic.c from the (new) DT property "bidirectional" simply?

I see your point. It would cut down from every driver out there
inventing some new property or config instead of everyone just sharing
a fixed set.
Maybe someone else out there will end up having a need for a
"bidirectional" option.

I was thinking about that one. It is a bit weird electrically, like what
kind of electronics is really bidirectional?

It seems like a fancy name for open drain/open source, what we
call "single ended" configuration. (See docs in
Documentation/gpio/driver.txt)

It would be great if you could check if that is what they mean,
actually.

But, what do we do for Ethernet? All the pins are "normal" except just
the MDIO pin needs to be bidirectional.

I see Geert clarified what we could do here.

Yours,
Linus Walleij