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

Venu Byravarasu
2013-01-18T05:42:14Z

> -----Original Message-----
> From: Venu Byravarasu
> Sent: Friday, January 18, 2013 10:26 AM
> To: 'Alan Stern'
> Cc: gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org; balbi-l0cyMroinI0@public.gmane.org; linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org;
> linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org; linux-
> tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Subject: RE: [PATCH v2 4/4] usb: Add APIs to access host registers from Tegra
> PHY
>
> > -----Original Message-----
> > From: Alan Stern [mailto:stern-nwvwT67g6+6dFdvTe/nMLpVzexx5G7lz@public.gmane.org]
> > Sent: Thursday, January 17, 2013 8:45 PM
> > To: Venu Byravarasu
> > Cc: gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org; balbi-l0cyMroinI0@public.gmane.org; linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org;
> > linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org; linux-
> > tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.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-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> > > ---
> > > 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.

Any ways, as we're just adding OCC for proper RWC treatment, I don't
see any harm in adding it to the list.
Hence will update the patch with two changes mentioned by Alan.

>
> >
> > Alan Stern