[PATCH] pinctrl: rockchip: enable clock when reading pin direction register

[PATCH] pinctrl: rockchip: enable clock when reading pin direction register

[Brian Norris]

We generally leave the GPIO clock disabled, unless an interrupt is
requested or we're accessing IO registers. We forgot to do this for the
->get_direction() callback, which means we can sometimes [1] get
incorrect results [2] from, e.g., /sys/kernel/debug/gpio.

Enable the clock, so we get the right results!

[1] Sometimes, because many systems have 1 or mor interrupt requested on
each GPIO bank, so they always leave their clock on.

[2] Incorrect, meaning the register returns 0, and so we interpret that
as "input".

Signed-off-by: Brian Norris <briannorris@chromium.org>
---
 drivers/pinctrl/pinctrl-rockchip.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/pinctrl/pinctrl-rockchip.c b/drivers/pinctrl/pinctrl-rockchip.c
index 2ba17548ad5b..073de6a9ed34 100644
--- a/drivers/pinctrl/pinctrl-rockchip.c
+++ b/drivers/pinctrl/pinctrl-rockchip.c
@@ -2014,8 +2014,16 @@ static int rockchip_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
 {
 	struct rockchip_pin_bank *bank = gpiochip_get_data(chip);
 	u32 data;
+	int ret;
 
+	ret = clk_enable(bank->clk);
+	if (ret < 0) {
+		dev_err(bank->drvdata->dev,
+			"failed to enable clock for bank %s\n", bank->name);
+		return ret;
+	}
 	data = readl_relaxed(bank->reg_base + GPIO_SWPORT_DDR);
+	clk_disable(bank->clk);
 
 	return !(data & BIT(offset));
 }
-- 
2.15.1.424.g9478a66081-goog

Re: [PATCH] pinctrl: rockchip: enable clock when reading pin direction register

[Heiko Stuebner]

Hi Brian,

Am Dienstag, 12. Dezember 2017, 09:43:43 CET schrieb Brian Norris:
> We generally leave the GPIO clock disabled, unless an interrupt is
> requested or we're accessing IO registers. We forgot to do this for the
> ->get_direction() callback, which means we can sometimes [1] get
> incorrect results [2] from, e.g., /sys/kernel/debug/gpio.
> 
> Enable the clock, so we get the right results!
> 
> [1] Sometimes, because many systems have 1 or mor interrupt requested on
> each GPIO bank, so they always leave their clock on.
> 
> [2] Incorrect, meaning the register returns 0, and so we interpret that
> as "input".
> 
> Signed-off-by: Brian Norris <briannorris@chromium.org>

thanks for catching this and it looks good to me, so
Reviewed-by: Heiko Stuebner <heiko@sntech.de>

Re: [PATCH] pinctrl: rockchip: enable clock when reading pin direction register

[Linus Walleij]

On Tue, Dec 12, 2017 at 6:43 PM, Brian Norris <briannorris@chromium.org> wrote:

> We generally leave the GPIO clock disabled, unless an interrupt is
> requested or we're accessing IO registers. We forgot to do this for the
> ->get_direction() callback, which means we can sometimes [1] get
> incorrect results [2] from, e.g., /sys/kernel/debug/gpio.
>
> Enable the clock, so we get the right results!
>
> [1] Sometimes, because many systems have 1 or mor interrupt requested on
> each GPIO bank, so they always leave their clock on.
>
> [2] Incorrect, meaning the register returns 0, and so we interpret that
> as "input".
>
> Signed-off-by: Brian Norris <briannorris@chromium.org>

Patch applied with Heiko's review tag.

Yours,
Linus Walleij