Re: [PATCH 3/5] mmc: slot-gpio: use gpiod_set_active_[low|high]()

[Bartosz Golaszewski <brgl@xxxxxxxx>]

On Wed, Sep 13, 2023 at 2:24 PM Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
>
> On Wed, Sep 13, 2023 at 1:50 PM Bartosz Golaszewski <brgl@xxxxxxxx> wrote:
>
> > From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
> >
> > We have new, less cumbersome and clearer interfaces for controlling GPIO
> > polarity. Use them in the MMC code.
> >
> > Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
>
> I like the looks of the code better, obviously but this looks like this for
> a reason unfortunately.
>
> See the following from
> Documentation/devicetree/bindings/mmc/mmc-controller.yaml:
>
>   # CD and WP lines can be implemented on the hardware in one of two
>   # ways: as GPIOs, specified in cd-gpios and wp-gpios properties, or
>   # as dedicated pins. Polarity of dedicated pins can be specified,
>   # using *-inverted properties. GPIO polarity can also be specified
>   # using the GPIO_ACTIVE_LOW flag. This creates an ambiguity in the
>   # latter case. We choose to use the XOR logic for GPIO CD and WP
>   # lines.  This means, the two properties are "superimposed," for
>   # example leaving the GPIO_ACTIVE_LOW flag clear and specifying the
>   # respective *-inverted property property results in a
>   # double-inversion and actually means the "normal" line polarity is
>   # in effect.
>

I hate it, thanks. :)

> Will you still provide the desired "double inversion" after this patch?
>

Not in the current form. Would it work to go:

if (override_active_level) {
    if (!(host->caps2 & MMC_CAP2_CD_ACTIVE_HIGH))
        gpiod_set_active_high(desc);
    else
        gpiod_set_active_low(desc);
} else {
    if (host->caps2 & MMC_CAP2_CD_ACTIVE_HIGH)
        gpiod_set_active_high(desc);
    else
        gpiod_set_active_low(desc);
}

?

Alternatively we could reimplement the toggle semantics locally in a
helper function in order to get rid of it from GPIOLIB.

Bart