linux-kernel - pinctrl: intel: Fix a glitch when updating IRQ flags on a preconfigured line

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Date:   Fri, 21 Jan 2022 17:34:26 +0800
From:   Grace Kao <grace.kao@...el.com>
To:     linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Andy Shevchenko <andy@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Kane Chen <kane.chen@...el.com>, grace.kao@...el.com,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: pinctrl: intel: Fix a glitch when updating IRQ flags on a preconfigured line

From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

The commit af7e3eeb84e2 ("pinctrl: intel: Disable input and output buffer
when switching to GPIO") hadn't taken into account an update of the IRQ
flags scenario.

When updating the IRQ flags on the preconfigured line the ->irq_set_type()
is called again. In such case the sequential Rx buffer configuration
changes may trigger a falling or rising edge interrupt that may lead,
on some platforms, to an undesired event.

This may happen because each of intel_gpio_set_gpio_mode() and
__intel_gpio_set_direction() updates the pad configuration with a different
value of the GPIORXDIS bit. Notable, that the intel_gpio_set_gpio_mode() is
called only for the pads that are configured as an input. Due to this fact,
integrate the logic of __intel_gpio_set_direction() call into the
intel_gpio_set_gpio_mode() so that the Rx buffer won't be disabled and
immediately re-enabled.

Fixes: af7e3eeb84e2 ("pinctrl: intel: Disable input and output buffer when switching to GPIO")
Reported-by: Kane Chen <kane.chen@...el.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
Tested-by: Grace Kao <grace.kao@...el.com>
Change-Id: I6ff5cf0c42a76dce709a445c1820c8f3a84d6d89
---
 drivers/pinctrl/intel/pinctrl-intel.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/pinctrl/intel/pinctrl-intel.c b/drivers/pinctrl/intel/pinctrl-intel.c
index 85750974d182..afd35e6999cc 100644
--- a/drivers/pinctrl/intel/pinctrl-intel.c
+++ b/drivers/pinctrl/intel/pinctrl-intel.c
@@ -451,8 +451,8 @@ static void intel_gpio_set_gpio_mode(void __iomem *padcfg0)
 	value &= ~PADCFG0_PMODE_MASK;
 	value |= PADCFG0_PMODE_GPIO;
 
-	/* Disable input and output buffers */
-	value |= PADCFG0_GPIORXDIS;
+	/* Disable TX buffer and enable RX (this will be input) */
+	value &= ~PADCFG0_GPIORXDIS;
 	value |= PADCFG0_GPIOTXDIS;
 
 	/* Disable SCI/SMI/NMI generation */
@@ -497,9 +497,6 @@ static int intel_gpio_request_enable(struct pinctrl_dev *pctldev,
 
 	intel_gpio_set_gpio_mode(padcfg0);
 
-	/* Disable TX buffer and enable RX (this will be input) */
-	__intel_gpio_set_direction(padcfg0, true);
-
 	raw_spin_unlock_irqrestore(&pctrl->lock, flags);
 
 	return 0;
@@ -1115,9 +1112,6 @@ static int intel_gpio_irq_type(struct irq_data *d, unsigned int type)
 
 	intel_gpio_set_gpio_mode(reg);
 
-	/* Disable TX buffer and enable RX (this will be input) */
-	__intel_gpio_set_direction(reg, true);
-
 	value = readl(reg);
 
 	value &= ~(PADCFG0_RXEVCFG_MASK | PADCFG0_RXINV);
-- 
2.17.1