Re: [PATCH v3] usb: core: verify devicetree nodes for USB devices

From: Marek Szyprowski
Date: Mon May 13 2019 - 05:09:34 EST

Hi Peter,

On 2019-05-13 11:00, Peter Chen wrote:
>> On 2019-05-10 05:10, Peter Chen wrote:
>>>> Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> writes:
>>>>> Commit 69bec7259853 ("USB: core: let USB device know device node")
>>>>> added support for attaching devicetree node for USB devices. The
>>>>> mentioned commit however identifies the given USB device node only by the
>> 'reg'
>>>>> property in the host controller children nodes. The USB device node
>>>>> however also has to have a 'compatible' property as described in
>>>>> Documentation/devicetree/bindings/usb/usb-device.txt. Lack for the
>>>>> 'compatible' property check might result in assigning a devicetree
>>>>> node, which is not intended to be the proper node for the given USB device.
>>>>> This is important especially when USB host controller has
>>>>> 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. Those
>>>>> binding predates support for USB devicetree nodes.
>>>>> Checking for the proper compatibility string allows to mitigate the
>>>>> conflict between USB device devicetree nodes and the bindings for
>>>>> USB controllers with child nodes. It also fixes the side-effect of
>>>>> the other commits, like 01fdf179f4b0 ("usb: core: skip interfaces
>>>>> disabled in devicetree"), which incorrectly disables some devices on
>>>>> Exynos based boards.
>>> Hi Marek,
>>> The purpose of your patch is do not set of_node for device under USB controller,
>> right?
>> Right.
> Do you mind doing it at function exynos_ehci_get_phy of ehci-exynos.c?

I don't mind fixing it in ehci-exynos, but frankly so far I have no idea
how to do it. The problem is that newly created USB devices get of-node
pointer pointing to a node which if not intended for them. How this can
be fixed in ehci-exynos?

Best regards
Marek Szyprowski, PhD
Samsung R&D Institute Poland