diff mbox series

[v1,01/10] pinctrl: intel: Disable input and output buffer when switching to GPIO

Message ID 20200610183543.89414-1-andriy.shevchenko@linux.intel.com
State Accepted
Commit af7e3eeb84e27fcfd1f46a80f111c8c72c206776
Headers show
Series [v1,01/10] pinctrl: intel: Disable input and output buffer when switching to GPIO | expand

Commit Message

Andy Shevchenko June 10, 2020, 6:35 p.m. UTC 
It's possible scenario that pin has been in different mode, while
the respective GPIO register has a leftover output buffer enabled.
In such case when we request GPIO it will switch to GPIO mode, and
thus to output with unknown value, followed by switching to input
mode. This can produce a glitch on the pin.

Disable input and output buffer when switching to GPIO to avoid
potential glitches.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/pinctrl/intel/pinctrl-intel.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/pinctrl/intel/pinctrl-intel.c b/drivers/pinctrl/intel/pinctrl-intel.c
index 6a274e20d926..9df5a0c0d416 100644
--- a/drivers/pinctrl/intel/pinctrl-intel.c
+++ b/drivers/pinctrl/intel/pinctrl-intel.c
@@ -435,11 +435,20 @@  static void intel_gpio_set_gpio_mode(void __iomem *padcfg0)
 {
 	u32 value;
 
+	value = readl(padcfg0);
+
 	/* Put the pad into GPIO mode */
-	value = readl(padcfg0) & ~PADCFG0_PMODE_MASK;
+	value &= ~PADCFG0_PMODE_MASK;
+	value |= PADCFG0_PMODE_GPIO;
+
+	/* Disable input and output buffers */
+	value &= ~PADCFG0_GPIORXDIS;
+	value &= ~PADCFG0_GPIOTXDIS;
+
 	/* Disable SCI/SMI/NMI generation */
 	value &= ~(PADCFG0_GPIROUTIOXAPIC | PADCFG0_GPIROUTSCI);
 	value &= ~(PADCFG0_GPIROUTSMI | PADCFG0_GPIROUTNMI);
+
 	writel(value, padcfg0);
 }
 
@@ -1036,6 +1045,9 @@  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);