On Wed, 19 Jul 2017, Peter Chen wrote:
> The controller driver may be NULL if the controller device
> is the middle device between platform device and roothub.
> This middle device may not need a device driver due to all
> hardware control can be at platform device driver, this
> platform device is usually a dual-role USB controller device.
>
> The benefit of using this middle device is we can keep both
> controller device's private data (known as struct usb_hcd)
> for USB core use, and platform device's private data for
> platform driver use.
>
> Signed-off-by: Peter Chen <peter.chen@xxxxxxx>
> ---
> Changes for v2:
> - Simplify the code per Alan's suggestion
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> drivers/usb/core/hub.c | 17 +++++++++++++++--
> 1 file changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index 4ee2a6a..acba56b 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -4383,6 +4383,7 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
> enum usb_device_speed oldspeed = udev->speed;
> const char *speed;
> int devnum = udev->devnum;
> + const char *driver_name;
>
> /* root hub ports have a slightly longer reset period
> * (from USB 2.0 spec, section 7.1.7.5)
> @@ -4450,11 +4451,23 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
> else
> speed = usb_speed_string(udev->speed);
>
> + /*
> + * The controller driver may be NULL if the controller device
> + * is the middle device between platform device and roothub.
> + * This middle device may not need a device driver due to
> + * all hardware control can be at platform device driver, this
> + * platform device is usually a dual-role USB controller device.
> + */
> + if (udev->bus->controller->driver)
> + driver_name = udev->bus->controller->driver->name;
> + else
> + driver_name = udev->bus->sysdev->driver->name;
> +
> if (udev->speed < USB_SPEED_SUPER)
> dev_info(&udev->dev,
> "%s %s USB device number %d using %s\n",
> (udev->config) ? "reset" : "new", speed,
> - devnum, udev->bus->controller->driver->name);
> + devnum, driver_name);
>
> /* Set up TT records, if needed */
> if (hdev->tt) {
> @@ -4586,7 +4599,7 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
> "%s SuperSpeed%s USB device number %d using %s\n",
> (udev->config) ? "reset" : "new",
> (udev->speed == USB_SPEED_SUPER_PLUS) ? "Plus" : "",
> - devnum, udev->bus->controller->driver->name);
> + devnum, driver_name);
> }
>
> /* cope with hardware quirkiness:
>
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