Re: [PATCH v2 0/1] watchdog: realtek-otto: Make use of regmap API

[Sander Vanheule <sander@svanheule.net>]

On Wed, 2026-07-01 at 18:48 +0000, Rustam Adilov wrote:
> Hello,
> On 2026-06-23 20:44, Sander Vanheule wrote:
> > Given the reason is endianess issues, does the GPIO driver (gpio-realtek-
> > otto.c)
> > using ioread32()/iowrite32() still work correctly? If you have the wrong
> > endianess there, you would only really see issues with the GPIO interrupt
> > handling.
> > 
> > If GPIO works correctly with CONFIG_SWAP_IO_SPACE enabled, then I suppose
> > the
> > watchdog driver needs to be amended. Otherwise perhaps the USB peripheral
> > driver
> > should be compensating for its endianess?
> 
> Actually, it is other way around. GPIO works correctly when
> CONFIG_SWAP_IO_SPACE
> is not enabled. When i do enable it, i need to patch the driver to make it
> work.
> The dirty patch is here [1], which simply changes ioread32()/iowrite32() to
> their __raw variants inside gpio_bank_read and gpio_bank_write the and what is
> also important, the GPIO_GENERIC_BIG_ENDIAN_BYTE_ORDER flag needs to be set.
> And also, i can't simply use the compatibles without GPIO_PORTS_REVERSED
> because
> the realtek_gpio_line_imr_pos is required for correct functionality.
> 
> This patch obviously won't cut as it is going to break rtl9300 without
> SWAP_IO_SPACE.
> Maybe we could make of gpio-regmap to handle swapping and stuff? I don't know
> of
> any other elegant solutions to this problem.
> 
> [1] -
> https://github.com/jameywine/openwrt/blob/bb94712cb6faccf082c5a9fcebfabddf837a16bb/target/linux/realtek/patches-6.18/814-gpio-realtek-otto-change-read-write-functions.patch

Looking at the full patch (*), I see you're not only modifying the GPIO,
watchdog and timer drivers, but also some very basic reset and pinctrl code to
have a functional system with SWAP_IO_SPACE. If SWAP_IO_SPACE requires you to
avoid byte-swapping in so many drivers, then you're just working around
SWAP_IO_SPACE. In other words, AFAICT it shouldn't be selected.

(*) https://github.com/jameywine/openwrt/commit/053aba620b12c6215e6760d8a613b4ebe05d452b

If there is a single new USB peripheral driver that only works with
SWAP_IO_SPACE, then I suggest you update that driver instead of enabling and
bypassing the effects of SWAP_IO_SPACE everywhere else.

Best,
Sander