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Subject[PATCH v3 6/6] gpio: max77620: Initialize hardware state of interrupts
Date
I noticed on Nexus 7 that after rebooting from downstream kernel to
upstream, the GPIO interrupt is triggering non-stop despite interrupts
being disabled for all of GPIOs. This happens because Nexus 7 uses a
soft-reboot, meaning that bootloader should take care of resetting
hardware, but the bootloader doesn't do it well. As a result, GPIO
interrupt may be left ON at a boot time. Let's mask all GPIO interrupts
at the driver's initialization time in order to resolve the issue.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
drivers/gpio/gpio-max77620.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)

diff --git a/drivers/gpio/gpio-max77620.c b/drivers/gpio/gpio-max77620.c
index 6c516aa7732d..e090979659eb 100644
--- a/drivers/gpio/gpio-max77620.c
+++ b/drivers/gpio/gpio-max77620.c
@@ -260,6 +260,30 @@ static int max77620_gpio_set_config(struct gpio_chip *gc, unsigned int offset,
return -ENOTSUPP;
}

+static int max77620_gpio_irq_init_hw(struct gpio_chip *gc)
+{
+ struct max77620_gpio *gpio = gpiochip_get_data(gc);
+ unsigned int i;
+ int err;
+
+ /*
+ * GPIO interrupts may be left ON after bootloader, hence let's
+ * pre-initialize hardware to the expected state by disabling all
+ * the interrupts.
+ */
+ for (i = 0; i < MAX77620_GPIO_NR; i++) {
+ err = regmap_update_bits(gpio->rmap, GPIO_REG_ADDR(i),
+ MAX77620_CNFG_GPIO_INT_MASK, 0);
+ if (err < 0) {
+ dev_err(gpio->dev,
+ "failed to disable interrupt: %d\n", err);
+ return err;
+ }
+ }
+
+ return 0;
+}
+
static int max77620_gpio_probe(struct platform_device *pdev)
{
struct max77620_chip *chip = dev_get_drvdata(pdev->dev.parent);
@@ -295,6 +319,7 @@ static int max77620_gpio_probe(struct platform_device *pdev)
mgpio->gpio_chip.irq.chip = &max77620_gpio_irqchip;
mgpio->gpio_chip.irq.default_type = IRQ_TYPE_NONE;
mgpio->gpio_chip.irq.handler = handle_edge_irq;
+ mgpio->gpio_chip.irq.init_hw = max77620_gpio_irq_init_hw,
mgpio->gpio_chip.irq.threaded = true;

platform_set_drvdata(pdev, mgpio);
--
2.26.0
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