linux-kernel - Re: [PATCH v1 2/5] extcon: Return -EPROBE_DEFER when extcon device is not found

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Date:   Wed, 14 Nov 2018 08:52:35 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        linux-usb@...r.kernel.org, Felipe Balbi <balbi@...nel.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Roger Quadros <rogerq@...com>, linux-pm@...r.kernel.org,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Sebastian Reichel <sre@...nel.org>, linux-omap@...r.kernel.org,
        Darren Hart <dvhart@...radead.org>,
        platform-driver-x86@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, Chen-Yu Tsai <wens@...e.org>,
        Hans de Goede <hdegoede@...hat.com>
Subject: Re: [PATCH v1 2/5] extcon: Return -EPROBE_DEFER when extcon device
 is not found

Hi Andy,

I was thinking about again to change from NULL to EPROBE_DEFER.

extcon_get_extcon_dev() function was almost called in the probe function.
But, this function might be called on other position instead of probe.

ENODEV is more correct error instead of EPROBE_DEFER.

Sorry. I'll withdraw my opinion related acked-by tag until we are clarifying it.

On 2018년 11월 12일 09:24, Chanwoo Choi wrote:
> Hi Andy,
> 
> On 2018년 11월 11일 03:10, Andy Shevchenko wrote:
>> All current users of extcon_get_extcon_dev() API considers
>> an extcon device a mandatory to appear. Thus, they all convert
>> NULL pointer to -EPROBE_DEFER error code.
>>
>> There is one more caller anticipated with the same requirements.
>>
>> To decrease a code duplication and a burden to the callers,
>> return -EPROBE_DEFER directly from extcon_get_extcon_dev().
>>
>> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
>> ---
>>  drivers/extcon/extcon-axp288.c        | 4 ++--
>>  drivers/extcon/extcon.c               | 2 +-
>>  drivers/power/supply/axp288_charger.c | 8 ++++----
>>  drivers/usb/phy/phy-omap-otg.c        | 6 +++---
>>  drivers/usb/typec/tcpm/fusb302.c      | 4 ++--
>>  5 files changed, 12 insertions(+), 12 deletions(-)
> 
> Acked-by: Chanwoo Choi <cw00.choi@...sung.com>
> 
> Best Regards,
> Chanwoo Choi
> 
>>
>> diff --git a/drivers/extcon/extcon-axp288.c b/drivers/extcon/extcon-axp288.c
>> index a983708b77a6..3472d3b756ed 100644
>> --- a/drivers/extcon/extcon-axp288.c
>> +++ b/drivers/extcon/extcon-axp288.c
>> @@ -360,8 +360,8 @@ static int axp288_extcon_probe(struct platform_device *pdev)
>>  		name = acpi_dev_get_first_match_name("INT3496", NULL, -1);
>>  		if (name) {
>>  			info->id_extcon = extcon_get_extcon_dev(name);
>> -			if (!info->id_extcon)
>> -				return -EPROBE_DEFER;
>> +			if (IS_ERR(info->id_extcon))
>> +				return PTR_ERR(info->id_extcon);
>>  
>>  			dev_info(dev, "controlling USB role\n");
>>  		} else {
>> diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c
>> index 5ab0498be652..2bd0f2f33f05 100644
>> --- a/drivers/extcon/extcon.c
>> +++ b/drivers/extcon/extcon.c
>> @@ -884,7 +884,7 @@ struct extcon_dev *extcon_get_extcon_dev(const char *extcon_name)
>>  		if (!strcmp(sd->name, extcon_name))
>>  			goto out;
>>  	}
>> -	sd = NULL;
>> +	sd = ERR_PTR(-EPROBE_DEFER);


(snip)

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics