[PATCH] usb: ehci-mx6: Enable OTG detection on imx8mm and imx8mn

[Adam Ford]

On Wed, Dec 22, 2021 at 1:31 PM Marek Vasut <marex at denx.de> wrote:

> On 12/22/21 13:52, Adam Ford wrote:
> > The imx8mm and imx8mn appear compatible with imx7d-usb
> > flags in the OTG driver.  If the dr_mode is defined as
> > host or peripheral, the device appears to operate correctly,
> > however the auto host/peripheral detection results in an error.
> >
> > Simply adding checks in ehci_usb_phy_mode for 8mm and
> > 8mn in ehci_usb_phy_mode is not enough, because ehci_usb_of_to_plat
> > is run before the clock is enabled which results in a hang.
> >
> > Enable the USB clock in ehci_usb_of_to_plat and add checks in
> > ehci_usb_phy_mode for 8mm and 8mn to enable auto detection of
> > the OTG mode on i.MX8M Mini and Nano.
>
> I was under the impression that of_to_plat() was meant to parse DT into
> driver local data, so frobbing with clock there could be a problem,
> right ? +CC Simon.
>

If that's true, we'll likely need to move the functions from
ehci_usb_of_to_plat to the probe function to run after the clocks are
enabled, because the call to usb_get_dr_mode hangs without the clocks
running.  usb_get_dr_mode tells the driver if it's a host or device mode.

We could make a temporary clock instead of passing the clock to the priv
structure.  I intentionally shut the clock off as soon as we're finished
reading the register so it didn't collide with the existing functions.

adam

>
> > diff --git a/drivers/usb/host/ehci-mx6.c b/drivers/usb/host/ehci-mx6.c
> > index 1bd6147c76..fa0798171b 100644
> > --- a/drivers/usb/host/ehci-mx6.c
> > +++ b/drivers/usb/host/ehci-mx6.c
> > @@ -543,7 +543,7 @@ static int ehci_usb_phy_mode(struct udevice *dev)
> >                       plat->init_type = USB_INIT_DEVICE;
> >               else
> >                       plat->init_type = USB_INIT_HOST;
> > -     } else if (is_mx7()) {
> > +     } else if (is_mx7() || is_imx8mm() || is_imx8mn()) {
> >               phy_status = (void __iomem *)(addr +
> >                                             USBNC_PHY_STATUS_OFFSET);
> >               val = readl(phy_status);
> > @@ -561,11 +561,30 @@ static int ehci_usb_phy_mode(struct udevice *dev)
> >
> >   static int ehci_usb_of_to_plat(struct udevice *dev)
> >   {
> > +#if CONFIG_IS_ENABLED(CLK)
> > +     int ret = 0;
> > +     struct ehci_mx6_priv_data *priv = dev_get_priv(dev);
> > +
> > +     ret = clk_get_by_index(dev, 0, &priv->clk);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     ret = clk_enable(&priv->clk);
> > +     if (ret)
> > +             return ret;
> > +#endif
> > +
> >       struct usb_plat *plat = dev_get_plat(dev);
> >       enum usb_dr_mode dr_mode;
> >
> >       dr_mode = usb_get_dr_mode(dev_ofnode(dev));
> >
> > +#if CONFIG_IS_ENABLED(CLK)
> > +     ret = clk_disable(&priv->clk);
> > +     if (ret)
> > +             return ret;
> > +#endif
> > +
> >       switch (dr_mode) {
> >       case USB_DR_MODE_HOST:
> >               plat->init_type = USB_INIT_HOST;
>