[PATCH] usb: dwc3: Add support to reset usb ULPI phy

[Bin Meng]

On Fri, Mar 4, 2022 at 7:36 PM T Karthik Reddy <tkarthik at xilinx.com> wrote:
>
> Hi Bin Meng,
>
> > -----Original Message-----
> > From: Bin Meng <bmeng.cn at gmail.com>
> > Sent: Thursday, March 3, 2022 2:18 PM
> > To: Michal Simek <michals at xilinx.com>
> > Cc: U-Boot Mailing List <u-boot at lists.denx.de>; git <git at xilinx.com>; T
> > Karthik Reddy <tkarthik at xilinx.com>; Angus Ainslie <angus at akkea.ca>;
> > Kunihiko Hayashi <hayashi.kunihiko at socionext.com>; Marek Vasut
> > <marex at denx.de>; Michael Walle <michael at walle.cc>; Priyanka Jain
> > <priyanka.jain at nxp.com>; Simon Glass <sjg at chromium.org>
> > Subject: Re: [PATCH] usb: dwc3: Add support to reset usb ULPI phy
> >
> > On Wed, Feb 23, 2022 at 11:07 PM Michal Simek <michal.simek at xilinx.com>
> > wrote:
> > >
> > > From: T Karthik Reddy <t.karthik.reddy at xilinx.com>
> > >
> > > When usb PHY initialization is done, the PHY need to be reset.
> > >
> > > Signed-off-by: T Karthik Reddy <t.karthik.reddy at xilinx.com>
> > > Signed-off-by: Michal Simek <michal.simek at xilinx.com>
> > > ---
> > >
> > >  drivers/usb/dwc3/Kconfig        |  2 +-
> > >  drivers/usb/dwc3/dwc3-generic.c | 28
> > ++++++++++++++++++++++++++++
> > >  2 files changed, 29 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/usb/dwc3/Kconfig b/drivers/usb/dwc3/Kconfig index
> > > 62aa65bf0cd2..685bda3729e5 100644
> > > --- a/drivers/usb/dwc3/Kconfig
> > > +++ b/drivers/usb/dwc3/Kconfig
> > > @@ -25,7 +25,7 @@ config USB_DWC3_OMAP
> > >
> > >  config USB_DWC3_GENERIC
> > >         bool "Generic implementation of a DWC3 wrapper (aka dwc3 glue)"
> > > -       depends on DM_USB && USB_DWC3 && MISC
> > > +       depends on DM_USB && USB_DWC3 && MISC && DM_GPIO
> > >         help
> > >           Select this for Xilinx ZynqMP and similar Platforms.
> > >           This wrapper supports Host and Peripheral operation modes.
> > > diff --git a/drivers/usb/dwc3/dwc3-generic.c
> > > b/drivers/usb/dwc3/dwc3-generic.c index b1e019b5b91a..17d35a6dc60c
> > > 100644
> > > --- a/drivers/usb/dwc3/dwc3-generic.c
> > > +++ b/drivers/usb/dwc3/dwc3-generic.c
> > > @@ -25,6 +25,7 @@
> > >  #include <reset.h>
> > >  #include <clk.h>
> > >  #include <usb/xhci.h>
> > > +#include <asm/gpio.h>
> > >
> > >  struct dwc3_glue_data {
> > >         struct clk_bulk         clks;
> > > @@ -42,6 +43,7 @@ struct dwc3_generic_priv {
> > >         void *base;
> > >         struct dwc3 dwc3;
> > >         struct phy_bulk phys;
> > > +       struct gpio_desc ulpi_reset;
> > >  };
> > >
> > >  struct dwc3_generic_host_priv {
> > > @@ -77,6 +79,26 @@ static int dwc3_generic_probe(struct udevice *dev,
> > >         if (rc && rc != -ENOTSUPP)
> > >                 return rc;
> > >
> > > +       if (device_is_compatible(dev->parent, "xlnx,zynqmp-dwc3")) {
> > > +               rc = gpio_request_by_name(dev->parent, "reset-gpios", 0,
> > > +                                         &priv->ulpi_reset, GPIOD_ACTIVE_LOW);
> > > +               if (rc != -EBUSY && rc)
> > > +                       return rc;
> >
> > What happens if rc == -EBUSY?
>
> Every time we do usb reset, gpio is requested again and returns EBUSY.
> We want to avoid returning probe with error, if rc == -EBUSY.
>

What about the very first time it returns EBUSY?

Regards,
Bin