Re: [PATCH v3 2/2] Add GPIO support for Realtek DHC(Digital Home Center) RTD SoCs.

[Michael Walle]

Hi,

> > >> >> This driver enables configuration of GPIO direction, GPIO values,
> > >> >> GPIO debounce settings and handles GPIO interrupts.
> > >> >
> > >> >Why gpio-regmap can't be used?
> > >>
> > >> I will try to use gpio-remap in the next version.
> > >
> > >If it appears that it makes code uglier / complicated, please add the note
> > >somewhere to answer the above question.
> >
> > I've traced the gpio-regmap.c file. It appears that for the driver to 
> > register
> > gpio_irq_chip, it must create the irq_domain and add it into 
> > gpio_regmap_config.
> > Additionally, the driver needs to register the irq handler by itself.
> > However, this process can be managed by the gpiolib if the driver 
> > fills in the struct
> > gpio_irq_chip inside struct gpio_chip before invoking 
> > gpiochip_add_data.
>
> Hmm... I thought this is solvable issue.
> Michael, is there a limitation in GPIO regmap that this driver can't be 
> converted?

gpio-regmap is designed that regmap-irq (drivers/base/regmap/irq.c) can 
be
used. So, if regmap-irq fit this driver, then it can be used together 
with
gpio-regmap.

From a quick glance at the patch, it looks like the gpio portion might 
fit
gpio-regmap.

> > Moreover, apart from managing the registers for gpio direction and 
> > value, there
> > are several other registers that require access(interrupt enable, 
> > debounce...).
> > The GPIO IRQ status registers are located at different base addresses 
> > and are
> > not contiguous. It may need to create an additional regmap and assign 
> > the access
> > table to this regmap.
>
> AFAIK this is not a problem as you can provide your own xlate function 
> that
> will take care about register mapping.

Just for the gpio part. IIRC regmap has it own translation (regmap 
fields).

> > With the above consideration, I tend to keep using the existing 
> > method.
>
> I would like to hear from Michael if it's indeed a big obstacle.

So, regarding the irq portion, again, it must fit the regmap-irq. For 
the
additional requirement to set the debounce, you can add a .set_config to
gpio_regmap_config and supply your own set_config callback. See also 
[1].

-michael

[1] 
https://lore.kernel.org/linux-gpio/d4a6a640c373b6d939e147691efa596c@xxxxxxxx/