Re: [PATCH v3 09/12] usb: roles: Add Intel xHCI USB role switch driver

Heikki Krogerus
2018-02-26T11:42:17Z

On Mon, Feb 26, 2018 at 10:09:22AM +0100, Hans de Goede wrote:
> Various Intel SoCs (Cherry Trail, Broxton and others) have an internal USB
> role switch for swiching the OTG USB data lines between the xHCI host
> controller and the dwc3 gadget controller.
>
> Note on some Cherry Trail systems there is ACPI/AML code listening to
> edge interrupts on the id-pin (through an _AIE ACPI method) and switching
> the role between ROLE_HOST and ROLE_NONE based on the id-pin. Note it does
> not set the role to ROLE_DEVICE, because device-mode is usually not used
> under Windows.
>
> The presence of AML code which modifies the cfg0 reg (on some systems)
> means that our read/write/modify of cfg0 may race with the AML code
> doing the same to avoid this we take the global ACPI lock while doing
> the read/write/modify.
>
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

Thanks Hans!

--
heikki