linux-kernel - [PATCH AUTOSEL for 4.9 181/190] pinctrl: rockchip: enable clock when reading pin direction register

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Message-ID: <20180308045810.8041-181-alexander.levin@microsoft.com>
Date:   Thu, 8 Mar 2018 05:00:12 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
CC:     Brian Norris <briannorris@...omium.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.9 181/190] pinctrl: rockchip: enable clock when
 reading pin direction register

From: Brian Norris <briannorris@...omium.org>

[ Upstream commit 5c9d8c4f6b8168738a26bcf288516cc3a0886810 ]

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@...omium.org>
Reviewed-by: Heiko Stuebner <heiko@...ech.de>
Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 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 49bf7dcb7ed8..f826793e972c 100644
--- a/drivers/pinctrl/pinctrl-rockchip.c
+++ b/drivers/pinctrl/pinctrl-rockchip.c
@@ -1278,8 +1278,16 @@ 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));
 }
-- 
2.14.1