Re: [PATCH 10/13] arm64: dts: ti: k3-j7200: Enable GPIO nodes at the board level

[Andrew Davis]

On 8/7/23 10:42 AM, Nishanth Menon wrote:
> On 10:28-20230807, Andrew Davis wrote:
> > On 8/7/23 12:38 AM, Dhruva Gole wrote:
> > > Andrew,
> > >
> > > On 03/08/23 02:23, Andrew Davis wrote:
> > > > GPIO nodes defined in the top-level J7200 SoC dtsi files are incomplete
> > > > and may not be functional unless they are extended with pinmux and
> > > > device information.
> > > >
> > > > Disable the GPIO nodes in the dtsi files and only enable the ones that
> > > > are actually pinned out on a given board.
> > > >
> > > > Signed-off-by: Andrew Davis <afd@xxxxxx>
> > > > ---
> > > >    .../boot/dts/ti/k3-j7200-common-proc-board.dts | 18 ++++--------------
> > > >    arch/arm64/boot/dts/ti/k3-j7200-main.dtsi      |  4 ++++
> > > >    .../arm64/boot/dts/ti/k3-j7200-mcu-wakeup.dtsi |  2 ++
> > > >    3 files changed, 10 insertions(+), 14 deletions(-)
> > > >
> > > > diff --git a/arch/arm64/boot/dts/ti/k3-j7200-common-proc-board.dts b/arch/arm64/boot/dts/ti/k3-j7200-common-proc-board.dts
> > > > index dee9056f56051..4a5c4f36baeec 100644
> > > > --- a/arch/arm64/boot/dts/ti/k3-j7200-common-proc-board.dts
> > > > +++ b/arch/arm64/boot/dts/ti/k3-j7200-common-proc-board.dts
> > > > @@ -240,27 +240,17 @@ &main_uart3 {
> > > >        pinctrl-0 = <&main_uart3_pins_default>;
> > > >    };
> > > > -&main_gpio2 {
> > > > -    status = "disabled";
> > > > -};
> > > > -
> > > > -&main_gpio4 {
> > > > -    status = "disabled";
> > > > -};
> > > > -
> > > > -&main_gpio6 {
> > > > -    status = "disabled";
> > > > +&main_gpio0 {
> > > > +    status = "okay";
> > > > +    /* default pins */
> > >
> > > Small question, where is the pmx for main_gpio0? What does "default pins"
> > > refer to here? Where are they pinmuxed?
> >
> > Good question, where is the pmx for main_gpio0? I don't know, it was
> > never defined before either, we only are noticing this now as we are
> > disabling by default instead of leaving an unfinished node enabled
> > by default. (another benefit of this disabled by default scheme).
> >
> > What is really happening is GPIO nodes we tend to pinmux differently
> > than normal device nodes. Their pinmux selections tends to be spread
> > out in all the nodes that make use of these GPIO pins, not all together
> > here in this node.
> >
> > For instance in this device we use one of the main_gpio0 pins as a
> > GPIO toggled regulator, and we define the pinmux for it in that node
> > (see vdd-sd-dv-default-pins).
> >
> > We can either define the rest of the pins not used elsewhere
> > here, or we can consider GPIO an exception to the rule, I'd say
> > the latter is fine for now.
>
>
> GPIO pinmux are typically defined where they need - the only place where
> they are explicitly called out in gpio is when they are meant to be used by
> libgpio - typically in the case of dev boards.
>
> Just drop the comments of /* default pins */ - that is just mis-leading.

True, will drop the comment for v2.

Andrew