Re: [PATCH] usb: core: verify devicetree nodes for disabled interfaces

From: Måns Rullgård
Date: Tue May 07 2019 - 09:25:43 EST

Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> writes:

> Commit 01fdf179f4b0 ("usb: core: skip interfaces disabled in devicetree")
> add support for disabling given USB device interface by adding nodes to
> the USB host controller device. The mentioned commit however identifies
> the given USB interface node only by the 'reg' property in the host
> controller children nodes and then checks for their the 'status'. The USB
> device interface nodes however also has to have a 'compatible' property as
> described in Documentation/devicetree/bindings/usb/usb-device.txt. This is
> important, because USB host controller might have child-nodes for other
> purposes. For example, Exynos EHCI and OHCI drivers already define
> child-nodes for each physical root hub port and assigns respective PHY
> controller and parameters for them. This conflicts with the proposed
> approach and verifying for the presence of the compatible property fixes
> this issue without changing the devicetree bindings and the way the PHY
> controllers are handled by Exynos EHCI/OHCI drivers.
> Reported-by: Markus Reichl <m.reichl@xxxxxxxxxxxxx>
> Fixes: 01fdf179f4b0 ("usb: core: skip interfaces disabled in devicetree")
> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> ---
> drivers/usb/core/message.c | 1 +
> 1 file changed, 1 insertion(+)
> diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
> index 82239f27c4cc..cd455c4add25 100644
> --- a/drivers/usb/core/message.c
> +++ b/drivers/usb/core/message.c
> @@ -2007,6 +2007,7 @@ int usb_set_configuration(struct usb_device *dev, int configuration)
> struct usb_interface *intf = cp->interface[i];
> if (intf->dev.of_node &&
> + of_device_is_compatible(intf->dev.of_node, NULL) &&
> !of_device_is_available(intf->dev.of_node)) {
> dev_info(&dev->dev, "skipping disabled interface %d\n",
> intf->cur_altsetting->desc.bInterfaceNumber);
> --

This doesn't look right. of_device_is_compatible() with a NULL compat
argument always returns zero.

There also seems to be a broader incompatibility between the generic USB
bindings and the use of child nodes in the Exynos bindings.

Måns Rullgård