linux-kernel - Re: [PATCH v4 2/3] usb: phy: Add Qualcomm SS-USB and HS-USB drivers for DWC3 core

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Date:	Tue, 20 Aug 2013 16:06:03 +0100
From:	Pawel Moll <pawel.moll@....com>
To:	Kumar Gala <galak@...eaurora.org>
Cc:	"Ivan T. Ivanov" <iivanov@...sol.com>,
	"balbi@...com" <balbi@...com>,
	"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
	Mark Rutland <Mark.Rutland@....com>,
	"swarren@...dotorg.org" <swarren@...dotorg.org>,
	"ian.campbell@...rix.com" <ian.campbell@...rix.com>,
	"rob@...dley.net" <rob@...dley.net>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	"idos@...eaurora.org" <idos@...eaurora.org>,
	"mgautam@...eaurora.org" <mgautam@...eaurora.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
	Paul Zimmerman <paul.zimmerman@...opsys.com>
Subject: Re: [PATCH v4 2/3] usb: phy: Add Qualcomm SS-USB and HS-USB drivers
 for DWC3 core

On Tue, 2013-08-20 at 16:01 +0100, Kumar Gala wrote:
> On Aug 20, 2013, at 9:54 AM, Ivan T. Ivanov wrote:
> 
> > 
> > Hi, 
> > 
> > On Tue, 2013-08-20 at 09:33 -0500, Felipe Balbi wrote: 
> >> On Tue, Aug 20, 2013 at 05:09:11PM +0300, Ivan T. Ivanov wrote:
> >>> Hi,
> >>> 
> >>> On Tue, 2013-08-20 at 08:37 -0500, Felipe Balbi wrote: 
> >>>> Hi,
> >>>> 
> >>>> On Tue, Aug 20, 2013 at 04:32:23PM +0300, Ivan T. Ivanov wrote:
> >>>>>> On Tue, Aug 20, 2013 at 12:56:04PM +0300, Ivan T. Ivanov wrote:
> >>>>>>> From: "Ivan T. Ivanov" <iivanov@...sol.com>
> >>>>>>> 
> >>>>>>> These drivers handles control and configuration of the HS
> >>>>>>> and SS USB PHY transceivers. They are part of the driver
> >>>>>>> which manage Synopsys DesignWare USB3 controller stack
> >>>>>>> inside Qualcomm SoC's.
> >>>>>>> 
> >>>>>>> Signed-off-by: Ivan T. Ivanov <iivanov@...sol.com>
> >>>>>>> ---
> >>>>>>> drivers/usb/phy/Kconfig           |   11 ++
> >>>>>>> drivers/usb/phy/Makefile          |    2 +
> >>>>>>> drivers/usb/phy/phy-msm-dwc3-hs.c |  327 ++++++++++++++++++++++++++++++++
> >>>>>>> drivers/usb/phy/phy-msm-dwc3-ss.c |  374 +++++++++++++++++++++++++++++++++++++
> >>>>>> 
> >>>>>> please rename these PHY drivers, they have nothing to do with DWC3. PHYs
> >>>>>> don't care about the USB controller.
> >>>>> 
> >>>>> I think they are SNPS DesignWare PHY's, additionally
> >>>>> wrapped with Qualcomm logic. I could substitute "dwc3"
> >>>>> with just "dw", which will be more correct.
> >>>> 
> >>>> alright, thank you. Let's add Paul to the loop since he might have very
> >>>> good insight in the synopsys PHYs.
> >>>> 
> >>>> mental note: if any other platform shows up with Synopsys PHY, ask them
> >>>> to use this driver instead :-)
> >>> 
> >>> I really doubt that this will bi possible. Control of the PHY's is
> >>> not directly trough ULPI, UTMI or PIPE3 interfaces, but trough
> >>> QSCRATCH registers, which of course is highly Qualcomm specific.
> >> 
> >> isn't it a memory mapped IP ? doesn't synopsys provide their own set of
> >> registers ?
> > 
> > From what I see it is not directly mapped. How QSCRATCH write and
> > reads transactions are translated to DW IP is unclear to me.
> 
> 
> I think the question is how does SW access them?

I afraid the answer may be: "it depends on the SOC". In my past I had to
initialize a (SATA) PHY by implementing a software JTAG state machine,
as the PHY's registers were not memory mapped *at all*. And the IP
itself came from Synopsys, Cadence or yet another EDA company...

Paweł


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