When attempting to setup up a gpio hog, device probing would repeatedly
fail with -EPROBE_DEFERED errors. It was caused by a circular dependency
between the gpio and pinctrl frameworks. If the gpio-ranges property is
present in device tree, then the gpio framework will handle the gpio pin
registration and eliminate the circular dependency.
See Christian Lamparter's commit a86caa9ba5d7 ("pinctrl: msm: fix
gpio-hog related boot issues") for a detailed commit message that
explains the issue in much more detail. The code comment in this commit
came from Christian's commit.
Signed-off-by: Brian Masney <masneyb@xxxxxxxxxxxxx>
---
drivers/pinctrl/qcom/pinctrl-spmi-gpio.c | 21 +++++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)
diff --git a/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c b/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c
index a29efbe08f48..4c1ff9a1d156 100644
--- a/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c
+++ b/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c
@@ -1028,10 +1028,23 @@ static int pmic_gpio_probe(struct platform_device *pdev)
return ret;
}
- ret = gpiochip_add_pin_range(&state->chip, dev_name(dev), 0, 0, npins);
- if (ret) {
- dev_err(dev, "failed to add pin range\n");
- goto err_range;
+ /*
+ * For DeviceTree-supported systems, the gpio core checks the
+ * pinctrl's device node for the "gpio-ranges" property.
+ * If it is present, it takes care of adding the pin ranges
+ * for the driver. In this case the driver can skip ahead.
+ *
+ * In order to remain compatible with older, existing DeviceTree
+ * files which don't set the "gpio-ranges" property or systems that
+ * utilize ACPI the driver has to call gpiochip_add_pin_range().
+ */
+ if (!of_property_read_bool(dev->of_node, "gpio-ranges")) {
+ ret = gpiochip_add_pin_range(&state->chip, dev_name(dev), 0, 0,
+ npins);
+ if (ret) {
+ dev_err(dev, "failed to add pin range\n");
+ goto err_range;
+ }
}
return 0;
--
2.17.2
