From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= Subject: Re: [PATCH v2] usb: core: verify devicetree nodes for disabled interfaces Date: Wed, 08 May 2019 16:27:37 +0100 Message-ID: References: <106fc58c-1a4f-6605-41d7-b6031c5751a3@samsung.com> <20190508104434.3409-1-m.szyprowski@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT Return-path: In-Reply-To: (Marek Szyprowski's message of "Wed, 8 May 2019 15:49:22 +0200") Sender: linux-kernel-owner@vger.kernel.org To: Marek Szyprowski Cc: linux-usb@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Bartlomiej Zolnierkiewicz , Markus Reichl , Krzysztof Kozlowski List-Id: linux-samsung-soc@vger.kernel.org Marek Szyprowski writes: > Hi > > On 2019-05-08 13:46, Måns Rullgård wrote: >> Marek Szyprowski 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 bindings and the way the PHY controllers >>> are handled by Exynos EHCI/OHCI drivers. >>> >>> Reported-by: Markus Reichl >>> Fixes: 01fdf179f4b0 ("usb: core: skip interfaces disabled in devicetree") >>> Signed-off-by: Marek Szyprowski >>> --- >>> 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 e844bb7b5676..6f7d047392bd 100644 >>> --- a/drivers/usb/core/message.c >>> +++ b/drivers/usb/core/message.c >>> @@ -2009,6 +2009,7 @@ int usb_set_configuration(struct usb_device *dev, int configuration) >>> struct usb_interface *intf = cp->interface[i]; >>> >>> if (intf->dev.of_node && >>> + of_find_property(intf->dev.of_node, "compatible", NULL) && >>> !of_device_is_available(intf->dev.of_node)) { >>> dev_info(&dev->dev, "skipping disabled interface %d\n", >>> intf->cur_altsetting->desc.bInterfaceNumber); >>> -- >> I don't think this is the right approach. We don't want to be adding >> such checks everywhere the of_node is used. A better way might be to >> not set of_node at all in the absence of a proper "compatible" string. > > Right, this will be a better approach. I've just checked the code and a > simple check for 'compatible' property presence can be easily added in > drivers/usb/core/of.c in usb_of_get_device_node() and > usb_of_get_interface_node() functions. > > The second check could be added in drivers/usb/core/hub.c in > usb_new_device() - to ensure that the device's vid/pid matches of_node > compatible string. > > Is this okay? Or just add a latter one? I'm not sure where the best place to check is. Someone else will have to weigh in on that. >> Then there's the problem of how to resolve the incompatibility between >> the generic USB and Exynos bindings. One possible fix could be to use >> a child node of the controller node to represent the root hub. Since >> the driver currently doesn't work at all if a devicetree has nodes for >> USB devices, there should be no compatibility concerns. > > So far we don't have any use case for adding devicetree nodes for usb > devices under Exynos EHCI/OHCI hcd, so this shouldn't be a problem for now. None that you know of, that is. Regardless, the bindings are inconsistent, and that needs to be fixed. -- Måns Rullgård