[PATCH v2 3/4] gpio: realtek: Add driver for Realtek DHC RTD1625 SoC

[Yu-Chun Lin [林祐君]]

> Hi,
>
> On Thu Apr 30, 2026 at 11:58 AM CEST, Yu-Chun Lin [林祐君] wrote:
> >> >> 3. Hardware Debounce: We also need to support hardware debounce 
> >> >> settings per pin, which requires custom configuration via 
> >> >> set_config mapped to these specific per-pin registers.
> >> >
> >> > Just add a version of an optional .set_config() call to 
> >> > gpio-regmap.c to handle this using .reg_mask_xlate() per above and 
> >> > add a new GPIO_REGMAP_CONFIG_OP to the above enum, problem solved.
> >> >
> >> > If it seems too hard I can write patch 1 & 2 adding this 
> >> > infrastructure but I bet you can easily see what can be done with 
> >> > gpio-regmap.c here provided Michael W approves the idea.
> >> >
> >
> > Our .set_config requires mapping specific debounce time values to 
> > hardware-specific enums and applying a Write-Enable bit.
> >
> > Would it be better to allow drivers to assign a custom '.set_config' 
> > callback directly within 'struct gpio_regmap_config'?
>
> Yeah, I don't think there will be much code sharing of code/functionality
> for the .set_config callback. A custom .set_config was proposed many times in the past.
> 

Will add a new patch to support custom .set_config.

> > Additionally, I didn't mention this in my previous email. we also need 
> > to implement GPIO interrupts. Our hardware design does not fit well 
> > with 'regmap_irq_chip'. Therefore, I am planning to create our own 
> > 'irqdomain' and 'irqchip' ops to handle our cascaded interrupts.
> >
> > Because of this custom IRQ implementation, I would need to use 'readl()/writel()'
> > for the IRQ callbacks in the rtd1625 GPIO driver instead of the regmap APIs.
> > Do you have any suggestions on how to handle this gracefully while 
> > keeping it aligned with the regmap infrastructure?
>
> Why can't the MMIO regmap be used for that?
>
> -michael

I was worried about regmap overhead in atomic context, but MMIO regmap should
be fine. I'll convert the irqchip callbacks to use regmap in v3.

Best Regards,
Yu-Chun