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

[Marek Vasut]

On 2/3/22 22:20, 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>
> 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);

Is the USB GPCv2 power domain always ON at this point ? If it isn't, 
then this access will lock up the whole SoC.

You can check that easily by adding printf() into 
drivers/power/domain/imx8m-power-domain.c imx8m_power_domain_on() , and 
verify that printf() prints something before this ehci_usb_phy_mode() 
code is called.