linux-kernel - Re: [PATCH] USB: initialize or shutdown PHY when add or remove host controller

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Message-ID: <20130618080130.GC5461@arwen.pp.htv.fi>
Date:	Tue, 18 Jun 2013 11:01:30 +0300
From:	Felipe Balbi <balbi@...com>
To:	Chao Xie <chao.xie@...vell.com>
CC:	<gregkh@...uxfoundation.org>, <stern@...land.harvard.edu>,
	<rogerq@...com>, <balbi@...com>, <linux-usb@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <xiechao.mail@...il.com>
Subject: Re: [PATCH] USB: initialize or shutdown PHY when add or remove host
 controller

Hi,

On Tue, Jun 18, 2013 at 03:15:01AM -0400, Chao Xie wrote:
> Some controller need software to initialize PHY before add
> host controller, and shut down PHY after remove host controller.
> Add the generic code for these controllers so they do not need
> do it in its own host controller driver.
> 
> Signed-off-by: Chao Xie <chao.xie@...vell.com>
> ---
>  drivers/usb/core/hcd.c |   19 ++++++++++++++++++-
>  1 files changed, 18 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
> index d53547d..b26196b 100644
> --- a/drivers/usb/core/hcd.c
> +++ b/drivers/usb/core/hcd.c
> @@ -43,6 +43,7 @@
>  
>  #include <linux/usb.h>
>  #include <linux/usb/hcd.h>
> +#include <linux/usb/phy.h>
>  
>  #include "usb.h"
>  
> @@ -2531,12 +2532,22 @@ int usb_add_hcd(struct usb_hcd *hcd,
>  	 */
>  	set_bit(HCD_FLAG_RH_RUNNING, &hcd->flags);
>  
> +	/* Initialize the PHY before other hardware operation. */
> +	if (hcd->phy) {

this looks wrong for two reasons:

a) you're not grabbing the PHY here.

	You can't just assume another entity grabbed your PHY for you.

b) usb_get_phy() returns an error number

	so the proper check would be !IS_ERR()

-- 
balbi

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