linux-kernel - Re: [PATCH v2] extcon: fix extcon_get_extcon

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Date:   Thu, 16 Dec 2021 17:24:30 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     MyungJoo Ham <myungjoo.ham@...sung.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Sebastian Reichel <sre@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-usb@...r.kernel.org, linux-omap@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH v2] extcon: fix extcon_get_extcon_dev() error handling

On 12/16/21 4:52 PM, Dan Carpenter wrote:
> On Thu, Dec 16, 2021 at 03:39:46PM +0900, Chanwoo Choi wrote:
>> Hi Dan,
>>
>> First of all,  sorry for late reply.
>>
>> There is one issue. About this issue, I already discussed on patch[1]
>> [1] https://lore.kernel.org/lkml/5BEB63C3.1020504@samsung.com/ 
>>
>> extcon_get_extcon_dev() is used for anywhere except for probe step.
>> But EPROBE_DEFER is only used on probe step.
>>
>> So that it is not clear to return EPROBE_DEFER from extcon_get_extcon_dev()
>> because extcon_get_extcon_dev() never know either call it on probe function
>> or not.
> 
> Currently extcon_get_extcon_dev() is only called from probe so it's not
> an issue.

Even if extcon_get_extcon_dev() is used on probe until now,
it is possible to use on anywhere as I commented.

It is difficult to agree this approach without any other solution.

Basically, the subsystem core never know either probe time or not.
It means that this issue should be handled in each device driver.


> 
> It's impossible to know what future programmers will want, but I feel
> like this change probably makes it easier for them.




-- 
Best Regards,
Chanwoo Choi
Samsung Electronics