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

[T Karthik Reddy]

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.

Thanks
T Karthik

> 
> > +
> > +               /* Toggle ulpi to reset the phy. */
> > +               rc = dm_gpio_set_value(&priv->ulpi_reset, 1);
> > +               if (rc)
> > +                       return rc;
> > +
> > +               mdelay(5);
> > +
> > +               rc = dm_gpio_set_value(&priv->ulpi_reset, 0);
> > +               if (rc)
> > +                       return rc;
> > +
> > +               mdelay(5);
> > +       }
> > +
> >         if (device_is_compatible(dev->parent, "rockchip,rk3399-dwc3"))
> >                 reset_deassert_bulk(&glue->resets);
> >
> > @@ -98,6 +120,12 @@ static int dwc3_generic_remove(struct udevice
> > *dev,  {
> >         struct dwc3 *dwc3 = &priv->dwc3;
> >
> > +       if (device_is_compatible(dev->parent, "xlnx,zynqmp-dwc3")) {
> > +               struct gpio_desc *ulpi_reset = &priv->ulpi_reset;
> > +
> > +               dm_gpio_free(ulpi_reset->dev, ulpi_reset);
> > +       }
> > +
> >         dwc3_remove(dwc3);
> >         dwc3_shutdown_phy(dev, &priv->phys);
> >         unmap_physmem(dwc3->regs, MAP_NOCACHE);
> >
> 
> Regards,
> Bin