[PATCH V4] usb: ehci-mx6: Enable OTG detection on imx8mm and imx8mn

[Michael Walle]

Hi Adam,

it's nice to include people who made review comments in the follow-up
patches. I had to pull this out of the mailinglist again.

> 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>
> Tested-by: Tim Harvey <tharvey at gateworks.com>
> ---
> V4:  Fix 'err_clk' reference, so it is not encapsulated in
>      an ifdef making it available at all times.
> 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 t
> 
> diff --git a/drivers/usb/host/ehci-mx6.c b/drivers/usb/host/ehci-mx6.c
> index 1bd6147c76..060b02accc 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:


Don't you want to propagate the OTG mode to the init_type field? Maybe
it will be useful sometime and IMHO makes it easier to read the code...

> -		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) {

Because this implicitly also contains OTG mode, right? So despite
the comment, if the device tree includes OTG mode, this branch is
also taken.

Otherwise looks good to me:

Reviewed-by: Michael Walle <michael at walle.cc>

> +		ret = ehci_usb_phy_mode(dev);
> +		if (ret)
> +			goto err_clk;
> +		else
> +			priv->init_type = plat->init_type;
> +	}
> +
>  #if CONFIG_IS_ENABLED(DM_REGULATOR)
>  	ret = device_get_supply_regulator(dev, "vbus-supply",
>  					  &priv->vbus_supply);
> @@ -741,8 +754,8 @@ err_regulator:
>  #if CONFIG_IS_ENABLED(DM_REGULATOR)
>  	if (priv->vbus_supply)
>  		regulator_set_enable(priv->vbus_supply, false);
> -err_clk:
>  #endif
> +err_clk:
>  #if CONFIG_IS_ENABLED(CLK)
>  	clk_disable(&priv->clk);
>  #else
> diff --git a/include/usb.h b/include/usb.h
> index f032de8af9..7e3796bd5b 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,
>  };
>  
>  /**********************************************************************