Hi Chanwoo Choi,
> Am 17.02.2020 um 11:15 schrieb Chanwoo Choi <cw00.choi@xxxxxxxxxxx>:
>
> Hi,
>
> On 2/17/20 5:55 PM, H. Nikolaus Schaller wrote:
>> If the gpios are probed after this driver (e.g. if they
>> come from an i2c expander) there is no need to print an
>> error message.
>>
>> Signed-off-by: H. Nikolaus Schaller <hns@xxxxxxxxxxxxx>
>> ---
>> drivers/extcon/extcon-palmas.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/extcon/extcon-palmas.c b/drivers/extcon/extcon-palmas.c
>> index edc5016f46f1..9c6254c0531c 100644
>> --- a/drivers/extcon/extcon-palmas.c
>> +++ b/drivers/extcon/extcon-palmas.c
>> @@ -206,14 +206,16 @@ static int palmas_usb_probe(struct platform_device *pdev)
>> palmas_usb->id_gpiod = devm_gpiod_get_optional(&pdev->dev, "id",
>> GPIOD_IN);
>> if (IS_ERR(palmas_usb->id_gpiod)) {
>> - dev_err(&pdev->dev, "failed to get id gpio\n");
>> + if (PTR_ERR(palmas_usb->id_gpiod) != -EPROBE_DEFER)
>> + dev_err(&pdev->dev, "failed to get id gpio\n");
>> return PTR_ERR(palmas_usb->id_gpiod);
>> }
>>
>> palmas_usb->vbus_gpiod = devm_gpiod_get_optional(&pdev->dev, "vbus",
>> GPIOD_IN);
>> if (IS_ERR(palmas_usb->vbus_gpiod)) {
>> - dev_err(&pdev->dev, "failed to get vbus gpio\n");
>> + if (PTR_ERR(palmas_usb->vbus_gpiod) != -EPROBE_DEFER)
>> + dev_err(&pdev->dev, "failed to get vbus gpio\n");
>> return PTR_ERR(palmas_usb->vbus_gpiod);
>> }
>>
>>
>
> Usually, gpio driver like pinctrl is very early probed
> because almost device drivers should use gpio.
> So, I have not any experience about this situation.
> Do you meet this situation on any h/w board?
Yes, I have experienced that sometimes on omap5+palmas based boards.
It seems to be this:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/omap5-board-common.dtsi?h=v5.6-rc2#n384
The extcon_usb3 can potentially match this extcon-palmas driver at
a moment where the palmas_gpio it is referring to has not yet been
successfully probed. Then the palmas_gpio would return -EPROBE_DEFER.
AFAIK there is no guarantee for a specific sequence of drivers
being probed and it is pure luck that in most cases the gpios
are already probed.
BR and thanks,
Nikolaus Schaller
