On Mon, 29 Nov 2010, Sarah Sharp wrote:
> An xHCI host controller contains USB 2.0 and USB 3.0 ports, which can
> occur in any order in the PORTSC registers. We cannot read the port speed
> bits in the PORTSC registers at init time to determine the port speed,
> since those bits are only valid when a USB device is plugged into the
> port.
>
> Instead, we read the "Supported Protocol Capability" registers in the xHC
> Extended Capabilities space. Those describe the protocol, port offset in
> the PORTSC registers, and port count. We use those registers to create
> two arrays of pointers to the PORTSC registers, one for USB 3.0 ports, and
> another for USB 2.0 ports. A third array keeps track of the port protocol
> major revision, and is indexed with the internal xHCI port number.
>
> This will make it easy to keep track of the port types to handle the xHCI
> driver faking two roothubs. The two arrays of pointers can be used to
> index the port the USB core wants, and the third array can be used to map
> xHC port status change event to the correct roothub that should process
> that event.
> + /*
> + * Note we could have all USB 3.0 ports, or all USB 2.0 ports.
I don't think you can have all USB-3 ports unless there are no ports at
all. The spec requires each USB-3 port to have a corresponding USB-2
port.
> @@ -1234,6 +1252,14 @@ struct xhci_hcd {
> u32 suspended_ports[8]; /* which ports are
> suspended */
> unsigned long resume_done[MAX_HC_PORTS];
> + /* Is each xHCI roothub port a USB 3.0, USB 2.0, or USB 1.1 port? */
This comment is unclear; the port_array field doesn't answer the
question asked in the comment. Furthermore, none of the ports can be
USB 1.1 -- they all have to be USB-2 or USB-3.
> + u8 *port_array;
> + /* Array of pointers to USB 3.0 PORTSC registers */
> + u32 __iomem **usb3_ports;
> + unsigned int num_usb3_ports;
> + /* Array of pointers to USB 2.0 PORTSC registers */
> + u32 __iomem **usb2_ports;
> + unsigned int num_usb2_ports;
> };
Alan Stern
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
