Re: [PATCH v3] extcon: palmas: hide error messages if gpio returns -EPROBE_DEFER

H. Nikolaus Schaller
2020-02-17T18:38:31Z

Hi,

> Am 17.02.2020 um 19:29 schrieb Ladislav Michl <ladis@linux-mips.org>:
>
> On Mon, Feb 17, 2020 at 02:58:14PM +0100, H. Nikolaus Schaller wrote:
>>
>>> Am 17.02.2020 um 14:38 schrieb H. Nikolaus Schaller <hns@goldelico.com>:
>>>
>>> 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@goldelico.com>
>>> ---
>>> drivers/extcon/extcon-palmas.c | 8 ++++++--
>>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/extcon/extcon-palmas.c b/drivers/extcon/extcon-palmas.c
>>> index edc5016f46f1..cea58d0cb457 100644
>>> --- a/drivers/extcon/extcon-palmas.c
>>> +++ b/drivers/extcon/extcon-palmas.c
>>> @@ -205,14 +205,18 @@ 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)) {
>>> + if (PTR_ERR(palmas_usb->id_gpiod) == -EPROBE_DEFER) {
>>> + return -EPROBE_DEFER;
>>> + } else if (IS_ERR(palmas_usb->id_gpiod)) {
>>
>> Hm.
>>
>> While looking again at that: why do we need the "{" and "} else "?
>>
>> It should be sufficient to have
>>
>>> palmas_usb->id_gpiod = devm_gpiod_get_optional(&pdev->dev, "id",
>>> GPIOD_IN);
>>> + if (PTR_ERR(palmas_usb->id_gpiod) == -EPROBE_DEFER)
>>> + return -EPROBE_DEFER;
>>> if (IS_ERR(palmas_usb->id_gpiod)) {
>>
>> What do you think is better coding style here?
>
> How about something like this? (just an idea with some work left for you ;-))
>
> --- a/drivers/extcon/extcon-palmas.c
> +++ b/drivers/extcon/extcon-palmas.c
> @@ -206,8 +206,10 @@ 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");
> - return PTR_ERR(palmas_usb->id_gpiod);
> + status = PTR_ERR(palmas_usb->id_gpiod);
> + if (status != -EPROBE_DEFER)
> + dev_err(&pdev->dev, "failed to get id gpio: %d\n", status);
> + return status;
> }

Well, what would be the improvement?
It needs an additional variable and makes the change more complex.

The main suggestion by Chanwoo Choi was to move the check for EPROBE_DEFER
outside of the IS_ERR() because checking this first and then for EPROBE_DEFER
is not necessary.

If acceptable I'd prefer my last proposal. It just adds 2 LOC before
and without touching the existing if (IS_ERR(...)).

If the compiler is clever it can cache palmas_usb->id_gpiod in a register
which serves the same purpose as the status variable.

>
> palmas_usb->vbus_gpiod = devm_gpiod_get_optional(&pdev->dev, "vbus",

BR and thanks,
Nikolaus