On Sat, Feb 16, 2019 at 2:46 PM <marek.va...@gmail.com> wrote:
> From: Marek Vasut <marek.vasut+rene...@gmail.com>
>
> Since commit d6cd33ad7102 ("regulator: gpio: Convert to use descriptors")
> the GPIO regulator had inverted the polarity of the control GPIO. This
> problem manifested itself on systems with DT containing the following
> description (snippet from salvator-common.dtsi):
>
> gpios = <&gpio5 1 GPIO_ACTIVE_HIGH>;
> gpios-states = <1>;
> states = <3300000 1
> 1800000 0>;
>
> Prior to the aforementioned commit, the gpio-regulator code used
> gpio_request_array() to claim the GPIO(s) specified in the "gpios"
> DT node, while the commit changed that to devm_gpiod_get_index().
>
> The legacy gpio_request_array() calls gpio_request_one() and then
> gpiod_request(), which parses the DT flags of the "gpios" node and
> populates the GPIO descriptor flags field accordingly.
>
> The new devm_gpiod_get_index() calls gpiod_get_index(), then
> of_find_gpio(), of_get_named_gpiod_flags() with flags != NULL,
> and then of_gpio_flags_quirks(). Since commit a603a2b8d86e
> ("gpio: of: Add special quirk to parse regulator flags"),
> of_gpio_flags_quirks() contains a quirk for regulator-gpio
> which was never triggered by the legacy gpio_request_array()
> code path, but is triggered by devm_gpiod_get_index() code
> path.
>
> This quirk checks whether a GPIO is associated with a fixed
> or gpio-regulator and if so, checks two additional conditions.
> First, whether such GPIO is active-low, and if so, ignores the
> active-low flag. Second, whether the regulator DT node does
> have an "enable-active-high" property and if the property is
> NOT present, sets the GPIO flags as active-low.
>
> The second check triggers a problem, since it is applied to all
> GPIOs associated with a gpio-regulator, rather than only on the
> "enable" GPIOs, as the old code did. This changes the way the
> gpio-regulator interprets the DT description of the control
> GPIOs.
>
> The old code using gpio_request_array() explicitly parsed the
> "enable-active-high" DT property and only applied it to the
> GPIOs described in the "enable-gpios" DT node, and only if
> those were present.
>
> This patch fixes the quirk code by only applying the quirk
> to "enable-gpios", thus restoring the old behavior.
>
> Signed-off-by: Marek Vasut <marek.vasut+rene...@gmail.com>
> Cc: Geert Uytterhoeven <geert+rene...@glider.be>
> Cc: Jan Kotas <j...@cadence.com>
> Cc: Linus Walleij <linus.wall...@linaro.org>
> Cc: Mark Brown <broo...@kernel.org>
> Cc: Wolfram Sang <wsa+rene...@sang-engineering.com>
> Cc: linux-renesas-soc@vger.kernel.org
> To: linux-g...@vger.kernel.org
Patch applied for v5.1, the regulator and GPIO changes should work
fine together in -next and merge nicely in the merge window.
Bonus for a long and descriptive commit message and keeping
me company over the Facebook chat while fixing it up! :D
Yours,
Linus Walleij
