linux-kernel - Re: [PATCH] usb: phy: Restore deferred probing path

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Message-ID: <54AAE71F.2040809@wwwdotorg.org>
Date:	Mon, 05 Jan 2015 12:33:51 -0700
From:	Stephen Warren <swarren@...dotorg.org>
To:	balbi@...com, Thierry Reding <thierry.reding@...il.com>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: phy: Restore deferred probing path

On 12/23/2014 11:36 AM, Felipe Balbi wrote:
> On Thu, Dec 04, 2014 at 01:06:07PM +0100, Thierry Reding wrote:
>> From: Thierry Reding <treding@...dia.com>
>>
>> Commit 1290a958d48e ("usb: phy: propagate __of_usb_find_phy()'s error on
>> failure") broke platforms that rely on deferred probing to order probing
>> of PHY and host controller drivers. The reason is that the commit simply
>> propagates errors from __of_usb_find_phy(), which returns -ENODEV if no
>> PHY has been registered yet for a given device tree node. The only case
>> in which -EPROBE_DEFER would now be returned is if try_module_get() did
>> fail, which does not make sense.
>>
>> The correct thing to do is to return -EPROBE_DEFER if a PHY hasn't been
>> registered yet. The only condition under which it makes sense to return
>> -ENODEV is if the device tree node representing the PHY has been
>> disabled (via the status property) because in that case the PHY will
>> never be registered.
>>
>> This patch addresses the problem by making __of_usb_find_phy() return an
>> appropriate error code while keeping in line with the above-mentioned
>> commit to propagate error codes rather than overwriting them. At the
>> same time the check for a valid PHY is decoupled from the check for the
>> try_module_get() call and a separate error code is returned if the
>> latter fails.
>>
>> Signed-off-by: Thierry Reding <treding@...dia.com>
>
> you forgot to add the magic "Fixes: foo bar" here, I'll add it this
> time, but I've already sent my -rc2 pull request, so this will only show
> up on -rc3.

Presumably also add the following, since the patch fixes a regression in 
a previous kernel release:

Cc: stable # v3.18

?

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