linux-kernel - Re: [PATCHv6 01/19] usb: otg: Rename otg_transceiver to usb

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Message-ID: <20111109060649.GC23337@legolas.emea.dhcp.ti.com>
Date:	Wed, 9 Nov 2011 08:06:51 +0200
From:	Felipe Balbi <balbi@...com>
To:	Peter Chen <peter.chen@...escale.com>
Cc:	"ABRAHAM, KISHON VIJAY" <kishon@...com>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Felipe Balbi <balbi@...com>, Greg KH <gregkh@...e.de>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	Sascha Hauer <s.hauer@...gutronix.de>
Subject: Re: [PATCHv6 01/19] usb: otg: Rename otg_transceiver to usb_phy

On Wed, Nov 09, 2011 at 09:22:38AM +0800, Peter Chen wrote:
> On Tue, Nov 08, 2011 at 11:27:12AM +0530, ABRAHAM, KISHON VIJAY wrote:
> > Hi Heikki,
> > 
> > On Fri, Oct 28, 2011 at 6:05 PM, Heikki Krogerus
> > <heikki.krogerus@...ux.intel.com> wrote:
> > > This is the first step in separating USB transceivers from
> > > USB OTG utilities.
> > >
> > > Includes fixes to IMX code from Sascha Hauer.
> > 
> > I tend to defer with your opinion of renaming otg_transceiver to
> > usb_phy. According to me otg_transceiver should program hardware
> > mechanisms associated to VBUS, ID lines, etc.. and phy is responsible
> > for transmitting data over differential data lines (with its own
> > programming of phy_init, phy_shutdown, setting phy clocks etc..). So
> > in my opinion otg_transceiver and usb_phy should be two different and
> > separate entities.
> > 
> I am a little puzzled, are there two separate analog usb parts at OMap
> 's usb part? What the transceiver do? And what the phy do?

Kinda... there's one which is mostly digital inside the SoC handling
data lines and also comunicating VBUS/ID levels to the link but the
actual VBUS/ID comparators are outside of the SoC, inside the PMIC.

It's a bit of a pain, but I understand why they did it that way. It's
mostly for power management, although the same is likely to be
achievable by keeping everything in the PMIC.

-- 
balbi

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