linux-kernel - RE: [PATCH v2 4/4] usb: Add APIs to access host registers from Tegra PHY

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Message-ID: <D958900912E20642BCBC71664EFECE3E6E1A6F1069@BGMAIL02.nvidia.com>
Date:	Fri, 18 Jan 2013 10:26:17 +0530
From:	Venu Byravarasu <vbyravarasu@...dia.com>
To:	Alan Stern <stern@...land.harvard.edu>
CC:	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"balbi@...com" <balbi@...com>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"swarren@...dotorg.org" <swarren@...dotorg.org>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: RE: [PATCH v2 4/4] usb: Add APIs to access host registers from
 Tegra PHY

> -----Original Message-----
> From: Alan Stern [mailto:stern@...land.harvard.edu]
> Sent: Thursday, January 17, 2013 8:45 PM
> To: Venu Byravarasu
> Cc: gregkh@...uxfoundation.org; balbi@...com; linux-usb@...r.kernel.org;
> linux-kernel@...r.kernel.org; swarren@...dotorg.org; linux-
> tegra@...r.kernel.org
> Subject: Re: [PATCH v2 4/4] usb: Add APIs to access host registers from Tegra
> PHY
> 
> On Thu, 17 Jan 2013, Venu Byravarasu wrote:
> 
> > As Tegra PHY driver need to access one of the Host registers,
> > added few APIs to ehci tegra driver.
> >
> > Signed-off-by: Venu Byravarasu <vbyravarasu@...dia.com>
> > ---
> > delta from v1:
> > Taken care of RWC bits, while accessing PORTSC register.
> >
> >  drivers/usb/host/ehci-tegra.c     |   70
> ++++++++++++++++++++++++++++++++++++-
> >  drivers/usb/phy/tegra_usb_phy.c   |   51 +++++++--------------------
> >  include/linux/usb/tegra_usb_phy.h |    6 +++
> >  3 files changed, 88 insertions(+), 39 deletions(-)
> >
> > diff --git a/drivers/usb/host/ehci-tegra.c b/drivers/usb/host/ehci-tegra.c
> > index 55a9cde..6bbf66a 100644
> > --- a/drivers/usb/host/ehci-tegra.c
> > +++ b/drivers/usb/host/ehci-tegra.c
> > @@ -2,7 +2,7 @@
> >   * EHCI-compliant USB host controller driver for NVIDIA Tegra SoCs
> >   *
> >   * Copyright (C) 2010 Google, Inc.
> > - * Copyright (C) 2009 NVIDIA Corporation
> > + * Copyright (C) 2009 - 2013 NVIDIA Corporation
> >   *
> >   * This program is free software; you can redistribute it and/or modify it
> >   * under the terms of the GNU General Public License as published by the
> > @@ -33,6 +33,16 @@
> >  #define TEGRA_USB2_BASE			0xC5004000
> >  #define TEGRA_USB3_BASE			0xC5008000
> >
> > +/* PORTSC registers */
> > +#define USB_PORTSC1			0x184
> > +#define USB_PORTSC1_PTS(x)	(((x) & 0x3) << 30)
> > +#define USB_PORTSC1_PHCD	(1 << 23)
> > +#define USB_PORTSC1_WKOC	(1 << 22)
> > +#define USB_PORTSC1_WKDS	(1 << 21)
> > +#define USB_PORTSC1_WKCN	(1 << 20)
> > +#define USB_PORTSC1_PEC		(1 << 3)
> > +#define USB_PORTSC1_CSC		(1 << 1)
> 
> Why redefine these values when they are already defined in
> include/linux/usb/ehci_defs.h?

Agreed. Will remove all above defines except PHCD & PTS, as these two
fields are added by tegra SOC to PORTSC.

> 
> > @@ -605,6 +615,53 @@ static const struct dev_pm_ops
> tegra_ehci_pm_ops = {
> >
> >  #endif
> >
> > +/* Bits of PORTSC1, which will get cleared by writing 1 into them */
> > +#define TEGRA_PORTSC_RWC_BITS (USB_PORTSC1_CSC |
> USB_PORTSC1_PEC)
> 
> Likewise for this.  Not to mention that you forgot to include the
> overcurrent-change bit.

As OCC bit is "not supported" by Tegra20 SOC, did not include it.
Should I still add this, to be compliant with EHCI spec?
Based on your comments, I can update the patch and send for review.

> 
> Alan Stern

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