linux-kernel - Re: [PATCH V2] USB: initialize or shutdown PHY when add or remove host controller

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Message-ID: <20130625134324.GF20439@arwen.pp.htv.fi>
Date:	Tue, 25 Jun 2013 16:43:24 +0300
From:	Felipe Balbi <balbi@...com>
To:	Roger Quadros <rogerq@...com>
CC:	<balbi@...com>, Alan Stern <stern@...land.harvard.edu>,
	Chao Xie <xiechao.mail@...il.com>,
	Chao Xie <chao.xie@...vell.com>,
	Greg KH <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH V2] USB: initialize or shutdown PHY when add or remove
 host controller

On Tue, Jun 25, 2013 at 04:37:11PM +0300, Roger Quadros wrote:
> On 06/24/2013 10:36 PM, Felipe Balbi wrote:
> > On Thu, Jun 20, 2013 at 01:25:31PM -0400, Alan Stern wrote:
> >> On Thu, 20 Jun 2013, Felipe Balbi wrote:
> >>
> >>>> In fact, the PHY setting and handling is related to platform or SOC,
> >>>> and for different SOC they can
> >>>> have same EHCI HCD but they PHY handling can be different.
> >>>> Omap'a case is the example, and i think some other vendors may have
> >>>> silimar cases.
> >>>> From above point, It is better to leave the PHY initialization and
> >>>> shutdown to be done by each echi-xxx driver.
> >>>>
> >>>> So Alan and Felipe
> >>>> What are your ideas about it?
> >>>
> >>> If we have so many exceptions, then sure. But eventually, the common
> >>> case should be added generically with a flag so that non-generic cases
> >>> (like OMAP) can request to handle the PHY by themselves.
> >>>
> >>> Alan ?
> >>
> >> I don't have very strong feelings about this; Felipe has much more
> >> experience with these things.
> >>
> >> However, when the common case is added into the core, the simplest way
> >> to indicate that the HCD wants to handle the PHY(s) by itself will be
> >> to leave hcd->phy set to NULL or an ERR_PTR value.
> >>
> >> One important thing that hasn't been pointed out yet: When we move
> >> these calls into the core, the same patch must also remove those calls
> >> from the glue drivers that currently do set hcd->phy.  And it must make
> >> sure that the glue drivers which handle the PHY by themselves do not
> >> set hcd->phy.
> > 
> > perfect summary. Perhaps Roger could already work on private PHY handle
> > for ehci-omap.c and later we can start moving generic case to usbcore
> > without having to touch ehci-omap.c at all. Roger, any commetns ?
> > 
> 
> This looks fine to me. I don't have anything to add.

thanks :-)

-- 
balbi

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