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

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Message-ID: <20130618082428.GF5461@arwen.pp.htv.fi>
Date:	Tue, 18 Jun 2013 11:24:28 +0300
From:	Felipe Balbi <balbi@...com>
To:	Roger Quadros <rogerq@...com>
CC:	<balbi@...com>, Chao Xie <chao.xie@...vell.com>,
	<gregkh@...uxfoundation.org>, <stern@...land.harvard.edu>,
	<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 11:23:59AM +0300, Roger Quadros wrote:
> On 06/18/2013 11:01 AM, Felipe Balbi wrote:
> > 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.
> 
> Isn't that done in the controller drivers e.g. ehci-fsl.c, ohci-omap, etc?

right, and what I'm saying is that it should all be re-factored into
ehci-hcd core :-)

> If the controllers don't want HCD core to manage the PHY they can just set it
> to some error code.

they shouldn't have the choice, otherwise it'll be a bit of a PITA to
maintain the code. ehci core tries to grab the PHY, if it's not there,
try to continue anyway. Assume it's not needed.

-- 
balbi

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