On Wed, Aug 29, 2018 at 03:18:34PM +0200, Michael Grzeschik wrote:
> From: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
>
> When booting from USB it's sometimes observed that the USB stack on
> the remote host gets confused. This happens when we adjust the PLLs
> the USB controller is hanging on. The ROM just leaves the USB controller
> enabled when it passes control to the bootloader, so in case the usb
> clks are enabled make sure we reset the otg before doing any critical
> clock operations.
>
> This is currently done for i.MX50, i.MX51, i.MX53 and i.MX6, but a
> similar thing can happen on other i.MXes aswell.
>
> Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> Signed-off-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>
> ---
> diff --git a/arch/arm/mach-imx/include/mach/usb.h b/arch/arm/mach-imx/include/mach/usb.h
> index 85528d77e6..ab827e9fab 100644
> --- a/arch/arm/mach-imx/include/mach/usb.h
> +++ b/arch/arm/mach-imx/include/mach/usb.h
> @@ -14,4 +14,27 @@
> int imx6_usb_phy2_disable_oc(void);
> int imx6_usb_phy2_enable(void);
>
> +#define USBCMD 0x140
> +#define USB_CMD_RESET 0x00000002
> +
> +/*
> + * imx_disable_otg_controller - disable the USB OTG controller
> + * @base: The base address of the controller
It's imx_reset_otg_controller now. Fixed up while applying.
Sascha
> + *
> + * When booting from USB the ROM just leaves the controller enabled. This can
> + * have bad side effects when for example we change PLL frequencies. In this
> + * case it is seen that the hub the board is connected to gets confused and USB
> + * is no longer working properly on the remote host. This function disables the
> + * OTG controller. It should be called before the clocks the controller hangs on
> + * is fiddled with.
> + */
> +static inline void imx_reset_otg_controller(void __iomem *base)
> +{
> + u32 r;
> +
> + r = readl(base + USBCMD);
> + r |= USB_CMD_RESET;
> + writel(r, base + USBCMD);
> +}
> +
> #endif /* __MACH_USB_H_*/
> --
> 2.18.0
>
>
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