From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chanwoo Choi Subject: Re: [PATCH v1 2/5] extcon: Return -EPROBE_DEFER when extcon device is not found Date: Wed, 14 Nov 2018 18:48:44 +0900 Message-ID: <5BEBEF7C.7060003@samsung.com> References: <20181110181101.24557-1-andriy.shevchenko@linux.intel.com> <20181110181101.24557-2-andriy.shevchenko@linux.intel.com> <5BE8C821.5080002@samsung.com> <5BEB63C3.1020504@samsung.com> <5BEBE741.6050101@samsung.com> <20181114093652.GK10650@smile.fi.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Return-path: In-reply-to: <20181114093652.GK10650@smile.fi.intel.com> Sender: linux-kernel-owner@vger.kernel.org To: Andy Shevchenko Cc: MyungJoo Ham , USB , Felipe Balbi , Guenter Roeck , "Krogerus, Heikki" , rogerq@ti.com, Linux PM , "Rafael J. Wysocki" , Sebastian Reichel , Linux OMAP Mailing List , Darren Hart , Platform Driver , Greg Kroah-Hartman , Linux Kernel Mailing List , Chen-Yu Tsai , Hans de Goede List-Id: linux-omap@vger.kernel.org On 2018년 11월 14일 18:36, Andy Shevchenko wrote: > On Wed, Nov 14, 2018 at 06:13:37PM +0900, Chanwoo Choi wrote: >> On 2018년 11월 14일 17:35, Andy Shevchenko wrote: >>> On Wed, Nov 14, 2018 at 1:53 AM Chanwoo Choi wrote: >>> >>>> 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. >>> >>> *Might be* sounds like a theoretical thing, care to share what is in you mind? >>> Current users and more important the new coming one are *all* doing the same. >>> >>>> ENODEV is more correct error instead of EPROBE_DEFER. >>> >>> So, you are proposing to continue duplicating conversion from ENODEV >>> to EPROBE_DEFER in *each* caller? >> >> The extcon core don't know the caller situation is in either probe() or other position >> in the caller driver. The caller driver should decide the kind of error value >> by using the return value of extcon_get_extcon_dev(). >> >> extcon_get_extcon_dev() function cannot be modified for only one case. >> If some device driver call extcon_get_extcon_dev() out of probe() fuction, >> EPROBE_DEFER is not always correct. > > I agree with this, but look at the current state of affairs. All users do the same. > If we need to have another case we may consider this later. Because we know the potential wrong case of this change, I can't agree this change. If extcon_get_extcon_dev() returns ENODEV instead of EPROBE_DEFER, it is clear and then there are no problem on both current and future. > > API inside the kernel are not carved in the stone. > > -- Best Regards, Chanwoo Choi Samsung Electronics