[PATCH V3] usb: ehci-mx6: Enable OTG detection on imx8mm and imx8mn

[Marcel Ziswiler]

On Mon, 2022-01-17 at 18:21 -0600, 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.
> 
> The solution isn't just adding checks for imx8mm and imx8mn to
> the check for imx7, because the USB clock needs to be running
> to read from the USBNC_PHY_STATUS_OFFSET register or it will hang.
> 
> Marek requested that I not enable the clocks in ehci_usb_of_to_plat,
> so I modified that function to return an unknown state if the
> device tree does not explicitly state whether it is a host
> or a peripheral.
> 
> When the driver probes, it looks to see if it's in the unknown
> state, and only then will it read the register to auto-detect.
> 
> Signed-off-by: Adam Ford <aford173 at gmail.com>
> ---
> V3:  Keep ehci_usb_of_to_plat but add the ability to return
>      and unknown state instead of reading the register.
>      If the probe determines the states is unknown, it will
>      query the register after the clocks have been enabled.
>      Because of the slight behavior change, I removed any
>      review or tested tags.
> 
> V2:  Rename ehci_usb_of_to_plat to ehci_usb_dr_mode and call it
>      from the probe after the clocks are enabled, but before
>      the data is needed.
> 
> diff --git a/drivers/usb/host/ehci-mx6.c b/drivers/usb/host/ehci-mx6.c
> index 1bd6147c76..cf44e53ff7 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);
> @@ -573,9 +573,8 @@ static int ehci_usb_of_to_plat(struct udevice *dev)
>         case USB_DR_MODE_PERIPHERAL:
>                 plat->init_type = USB_INIT_DEVICE;
>                 break;
> -       case USB_DR_MODE_OTG:
> -       case USB_DR_MODE_UNKNOWN:
> -               return ehci_usb_phy_mode(dev);
> +       default:
> +               plat->init_type = USB_INIT_UNKNOWN;
>         };
>  
>         return 0;
> @@ -677,6 +676,20 @@ static int ehci_usb_probe(struct udevice *dev)
>         mdelay(1);
>  #endif
>  
> +       /*
> +        * If the device tree didn't specify host or device,
> +        * the default is USB_INIT_UNKNOWN, so we need to check
> +        * the register. For imx8mm and imx8mn, the clocks need to be
> +        * running first, so we defer the check until they are.
> +        */
> +       if (priv->init_type == USB_INIT_UNKNOWN) {
> +               ret = ehci_usb_phy_mode(dev);
> +               if (ret)
> +                       goto err_clk;

Hm, unfortunately, that label is gated by an ifdef leading to the following on colibri_imx7:

drivers/usb/host/ehci-mx6.c: In function ‘ehci_usb_probe’:
drivers/usb/host/ehci-mx6.c:688:4: error: label ‘err_clk’ used but not defined
  688 |    goto err_clk;
      |    ^~~~
make[1]: *** [scripts/Makefile.build:254: drivers/usb/host/ehci-mx6.o] Error 1

I have to admit that maybe we should indeed run it with DM_REGULATOR but that won't change anything on this
issue. I guess one should really not have any gotos to a label err_clk being ifdefed from somewhere not
ifdefed.

> +               else
> +                       priv->init_type = plat->init_type;
> +       }
> +
>  #if CONFIG_IS_ENABLED(DM_REGULATOR)
>         ret = device_get_supply_regulator(dev, "vbus-supply",
>                                           &priv->vbus_supply);
> diff --git a/include/usb.h b/include/usb.h
> index b3851fdb4f..47d738a786 100644
> --- a/include/usb.h
> +++ b/include/usb.h
> @@ -163,7 +163,8 @@ struct int_queue;
>   */
>  enum usb_init_type {
>         USB_INIT_HOST,
> -       USB_INIT_DEVICE
> +       USB_INIT_DEVICE,
> +       USB_INIT_UNKNOWN,
>  };
>  
>  /**********************************************************************