Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Content-Type: text/plain; charset=us-ascii
Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\))
Subject: Re: [PATCH v3] extcon: palmas: hide error messages if gpio returns -EPROBE_DEFER
From:   "H. Nikolaus Schaller" <hns@goldelico.com>
In-Reply-To: <20200217182906.GA140676@lenoch>
Date:   Mon, 17 Feb 2020 19:38:16 +0100
Cc:     MyungJoo Ham <myungjoo.ham@samsung.com>,
        Chanwoo Choi <cw00.choi@samsung.com>,
        linux-kernel@vger.kernel.org, letux-kernel@openphoenux.org,
        kernel@pyra-handheld.com, linux-omap@vger.kernel.org
Content-Transfer-Encoding: quoted-printable
Message-Id: <012228CC-2B49-4AAE-B574-92E44621F0D6@goldelico.com>
References: <d5c2826a5f00fcaee62f00662ae2a44dc4a5395d.1581946695.git.hns@goldelico.com> <C3D9F783-EE45-4681-93D9-C1407284CB59@goldelico.com> <20200217182906.GA140676@lenoch>
To:     Ladislav Michl <ladis@linux-mips.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi,

> Am 17.02.2020 um 19:29 schrieb Ladislav Michl <ladis@linux-mips.org>:
>=20
> On Mon, Feb 17, 2020 at 02:58:14PM +0100, H. Nikolaus Schaller wrote:
>>=20
>>> Am 17.02.2020 um 14:38 schrieb H. Nikolaus Schaller =
<hns@goldelico.com>:
>>>=20
>>> 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.
>>>=20
>>> Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
>>> ---
>>> drivers/extcon/extcon-palmas.c | 8 ++++++--
>>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>>=20
>>> 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)
>>>=20
>>> 	palmas_usb->id_gpiod =3D devm_gpiod_get_optional(&pdev->dev, =
"id",
>>> 							GPIOD_IN);
>>> -	if (IS_ERR(palmas_usb->id_gpiod)) {
>>> +	if (PTR_ERR(palmas_usb->id_gpiod) =3D=3D -EPROBE_DEFER) {
>>> +		return -EPROBE_DEFER;
>>> +	} else if (IS_ERR(palmas_usb->id_gpiod)) {
>>=20
>> Hm.
>>=20
>> While looking again at that: why do we need the "{" and "} else "?
>>=20
>> It should be sufficient to have
>>=20
>>> 	palmas_usb->id_gpiod =3D devm_gpiod_get_optional(&pdev->dev, =
"id",
>>> 							GPIOD_IN);
>>> +	if (PTR_ERR(palmas_usb->id_gpiod) =3D=3D -EPROBE_DEFER)
>>> +		return -EPROBE_DEFER;
>>> 	if (IS_ERR(palmas_usb->id_gpiod)) {
>>=20
>> What do you think is better coding style here?
>=20
> How about something like this? (just an idea with some work left for =
you ;-))
>=20
> --- 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 =3D 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 =3D PTR_ERR(palmas_usb->id_gpiod);
> +		if (status !=3D -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.

>=20
> 	palmas_usb->vbus_gpiod =3D devm_gpiod_get_optional(&pdev->dev, =
"vbus",

BR and thanks,
Nikolaus=