linux-kernel - [PATCH v2 2/7] pinctrl: armada-37xx: set GPIO output value before setting direction

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Message-Id: <20250514-pinctrl-a37xx-fixes-v2-2-07e9ac1ab737@gmail.com>
Date: Wed, 14 May 2025 21:18:33 +0200
From: Gabor Juhos <j4g8y7@...il.com>
To: Andrew Lunn <andrew@...n.ch>, 
 Gregory Clement <gregory.clement@...tlin.com>, 
 Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>, 
 Linus Walleij <linus.walleij@...aro.org>, 
 Bartosz Golaszewski <brgl@...ev.pl>
Cc: Imre Kaloz <kaloz@...nwrt.org>, linux-arm-kernel@...ts.infradead.org, 
 linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Gabor Juhos <j4g8y7@...il.com>, stable@...r.kernel.org
Subject: [PATCH v2 2/7] pinctrl: armada-37xx: set GPIO output value before
 setting direction

Changing the direction before updating the output value in the
OUTPUT_VAL register may result in a glitch on the output line
if the previous value in the OUTPUT_VAL register is different
from the one we want to set.

In order to avoid that, update the output value before changing
the direction.

Cc: stable@...r.kernel.org
Fixes: 6702abb3bf23 ("pinctrl: armada-37xx: Fix direction_output() callback behavior")
Signed-off-by: Imre Kaloz <kaloz@...nwrt.org>
Reviewed-by: Andrew Lunn <andrew@...n.ch>
Signed-off-by: Gabor Juhos <j4g8y7@...il.com>
---
Changes in v2:
  - swap with patch 3 from v1
  - add 'Reviewed-by' tag from Andrew
  - reorder 'Signed-off-by' tags (result of 'b4 trailers -u')
---
 drivers/pinctrl/mvebu/pinctrl-armada-37xx.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/pinctrl/mvebu/pinctrl-armada-37xx.c b/drivers/pinctrl/mvebu/pinctrl-armada-37xx.c
index 43034d29292687e875136aafa530b62479dc55ec..79f9c08e5039c31acb170d4f38b516b1454fd9ea 100644
--- a/drivers/pinctrl/mvebu/pinctrl-armada-37xx.c
+++ b/drivers/pinctrl/mvebu/pinctrl-armada-37xx.c
@@ -417,23 +417,22 @@ static int armada_37xx_gpio_direction_output(struct gpio_chip *chip,
 					     unsigned int offset, int value)
 {
 	struct armada_37xx_pinctrl *info = gpiochip_get_data(chip);
-	unsigned int val_offset = offset;
-	unsigned int reg = OUTPUT_EN;
+	unsigned int en_offset = offset;
+	unsigned int reg = OUTPUT_VAL;
 	unsigned int mask, val, ret;
 
 	armada_37xx_update_reg(&reg, &offset);
 	mask = BIT(offset);
+	val = value ? mask : 0;
 
-	ret = regmap_update_bits(info->regmap, reg, mask, mask);
-
+	ret = regmap_update_bits(info->regmap, reg, mask, val);
 	if (ret)
 		return ret;
 
-	reg = OUTPUT_VAL;
-	armada_37xx_update_reg(&reg, &val_offset);
+	reg = OUTPUT_EN;
+	armada_37xx_update_reg(&reg, &en_offset);
 
-	val = value ? mask : 0;
-	regmap_update_bits(info->regmap, reg, mask, val);
+	regmap_update_bits(info->regmap, reg, mask, mask);
 
 	return 0;
 }

-- 
2.49.0