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

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Message-ID: <20141217082958.GC3303@ulmo>
Date:	Wed, 17 Dec 2014 09:30:03 +0100
From:	Thierry Reding <thierry.reding@...il.com>
To:	Felipe Balbi <balbi@...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 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>
> ---
>  drivers/usb/phy/phy.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)

Ping?

Thierry

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