On Sat 10 Nov 17:34 PST 2018, Brian Masney wrote:
> 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@xxxxxxxxxxxxx>
Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
Regards,
Bjorn
> ---
> For the patch and discussion regarding pinctrl-spmi-gpio.c, see
> https://lore.kernel.org/lkml/20181101001149.13453-6-masneyb@xxxxxxxxxxxxx/
>
> 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 6b30bef829ab..ded7d765af2e 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);
> --
> 2.17.2
>
