Re: [PATCH 0/5] RTL8231 GPIO expander support

Sander Vanheule
2021-05-16T21:41:00Z

On Wed, 2021-05-12 at 18:29 +0300, Andy Shevchenko wrote:
>
>
> On Tuesday, May 11, 2021, Sander Vanheule <sander@svanheule.net> wrote:
> > The RTL8231 GPIO and LED expander can be configured for use as an MDIO or
> > SMI
> > bus device. Currently only the MDIO mode is supported, although SMI mode
> > support should be fairly straightforward, once an SMI bus driver is
> > available.
> >
> > Provided features by the RTL8231:
> >   - Up to 37 GPIOs
> >     - Configurable drive strength: 8mA or 4mA (currently unsupported)
> >     - Input debouncing on high GPIOs (currently unsupported)
> >   - Up to 88 LEDs in multiple scan matrix groups
> >     - On, off, or one of six toggling intervals
> >     - "single-color mode": 2×36 single color LEDs + 8 bi-color LEDs
> >     - "bi-color mode": (12 + 2×6) bi-color LEDs + 24 single color LEDs
> >   - Up to one PWM output (currently unsupported)
> >     - Fixed duty cycle, 8 selectable frequencies (1.2kHz - 4.8kHz)
> >
> > There remain some log warnings when probing the device, possibly due to the
> > way
> > I'm using the MFD subsystem. Would it be possible to avoid these?
> > [    2.602242] rtl8231-pinctrl: Failed to locate of_node [id: -2]
> > [    2.609380] rtl8231-pinctrl rtl8231-pinctrl.0.auto: no of_node; not
> > parsing pinctrl DT
> >
> > When no 'leds' sub-node is specified:
> > [    2.922262] rtl8231-leds: Failed to locate of_node [id: -2]
> > [    2.967149] rtl8231-leds rtl8231-leds.1.auto: no of_node; not parsing
> > pinctrl DT
> > [    2.975673] rtl8231-leds rtl8231-leds.1.auto: scan mode missing or
> > invalid
> > [    2.983531] rtl8231-leds: probe of rtl8231-leds.1.auto failed with error
> > -22
> >
> >
>
>
> I have several comments to the series, but I may give them next week.
>
> Just couple here:
> 1. If subsystem provides a regmap API I would suggest to use it, I.o.w. try
> again to understand what is wrong with MDIO case.

Are you referring to the MDIO regmap interface, or the GPIO regmap interface?

For the MDIO regmap interface, I have been able to resolve the Kconfig
dependency issue. So I can reintroduce that, if that's preferred over the
solution in this v1.

With an extra patch, I was able to use the gpio-regmap interface, dropping most
of the GPIO code. The current gpio-regmap implementation makes the assumption
that an output value can be set while a pin is configured as an input. That
assumption is invalid for this chip, so I had to provide an extra flag for
gpio_regmap_config, similar to how this is handled in gpio-mmio.

> 2. Please, switch to fwnode API in LED driver

Since you had the same comment on my previous patch set, I had already tried to
this this into account as much as possible.

There's a few things I couldn't find the fwnode-equivalent for:
* I use of_node_name_prefix to enforce the naming required by the binding. I
could just walk over all (available) child nodes, which would be mostly
equivalent.
* To get the address of an LED child node, I use of_get_address, since this
appeared to provide what I want to do: get the address of the node. I know
next to nothing about ACPI. Does the equivalent exist there? Or am I taking
the wrong approach?

I have updated patches ready, if you would rather just review a v2.

Best,
Sander