Hi,
> Am 17.02.2020 um 12:24 schrieb Chanwoo Choi <cw00.choi@xxxxxxxxxxx>:
>
> Hi,
>
> On 2/17/20 8:07 PM, H. Nikolaus Schaller wrote:
>> 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);
>>>> }
>
>
> How about editing it ? as following:
> because following suggestion reduces the one checking behavior
> when return value is -EPROBE_DEFER.
>
> if (PTR_ERR(palmas_usb->id_gpiod) == -EPROBE_DEFER) {
> return -EPROBE_DEFER;
> } else if (IS_ERR(palmas_usb->id_gpiod)) {
> dev_err(&pdev->dev, "failed to get id gpio\n");
> return PTR_ERR(palmas_usb->id_gpiod);
> }
Yes, looks indeed to be valid (some discussion around
is here: https://lore.kernel.org/patchwork/patch/999602/ ).
So I'll send an update asap.
>
>>>>
>>>> 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");
>
> ditto.
>
>>>> 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.
>
> Thanks for explaining the example.
BR and thanks,
Nikolaus Schaller
