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Subject[PATCH 4.9 029/199] pinctrl: qcom: ssbi-gpio: fix gpio-hog related boot issues
Date
From: Brian Masney <masneyb@onstation.org>

[ Upstream commit 7ed07855773814337b9814f1c3e866df52ebce68 ]

When attempting to setup up a gpio hog, device probing will repeatedly
fail with -EPROBE_DEFERED errors. It is 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.

I did not test this change against any hardware supported by this
particular driver, however I was able to validate this same fix works
for pinctrl-spmi-gpio.c using a LG Nexus 5 (hammerhead) phone.

Signed-off-by: Brian Masney <masneyb@onstation.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/pinctrl/qcom/pinctrl-ssbi-gpio.c | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/pinctrl/qcom/pinctrl-ssbi-gpio.c b/drivers/pinctrl/qcom/pinctrl-ssbi-gpio.c
index e86c4de2f6db1..92855f45bc537 100644
--- a/drivers/pinctrl/qcom/pinctrl-ssbi-gpio.c
+++ b/drivers/pinctrl/qcom/pinctrl-ssbi-gpio.c
@@ -762,12 +762,23 @@ static int pm8xxx_gpio_probe(struct platform_device *pdev)
return ret;
}

- ret = gpiochip_add_pin_range(&pctrl->chip,
- dev_name(pctrl->dev),
- 0, 0, pctrl->chip.ngpio);
- if (ret) {
- dev_err(pctrl->dev, "failed to add pin range\n");
- goto unregister_gpiochip;
+ /*
+ * 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(pctrl->dev->of_node, "gpio-ranges")) {
+ ret = gpiochip_add_pin_range(&pctrl->chip, dev_name(pctrl->dev),
+ 0, 0, pctrl->chip.ngpio);
+ if (ret) {
+ dev_err(pctrl->dev, "failed to add pin range\n");
+ goto unregister_gpiochip;
+ }
}

platform_set_drvdata(pdev, pctrl);
--
2.20.1


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