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From: "Måns Rullgård" <mans@mansr.com>
To: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Peter Chen <peter.chen@nxp.com>,
	"linux-usb\@vger.kernel.org" <linux-usb@vger.kernel.org>,
	"linux-samsung-soc\@vger.kernel.org" 
	<linux-samsung-soc@vger.kernel.org>,
	"linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Markus Reichl <m.reichl@fivetechno.de>,
	Krzysztof Kozlowski <krzk@kernel.org>
Subject: Re: [PATCH v3] usb: core: verify devicetree nodes for USB devices
Date: Mon, 13 May 2019 11:06:39 +0100	[thread overview]
Message-ID: <yw1xzhnqu0r4.fsf@mansr.com> (raw)
In-Reply-To: <5d0abe9c-613c-d39b-6746-78e5e5c2bbc5@samsung.com> (Marek Szyprowski's message of "Mon, 13 May 2019 12:03:18 +0200")

Marek Szyprowski <m.szyprowski@samsung.com> writes:

> Hi Peter,
>
> On 2019-05-13 11:23, Peter Chen wrote:
>>> On 2019-05-13 11:00, Peter Chen wrote:
>>>>> On 2019-05-10 05:10, Peter Chen wrote:
>>>>>>> Marek Szyprowski <m.szyprowski@samsung.com> 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?
>>>
>>   
>> Can't be workaround by setting of_node as NULL for EHCI controller or
>> for PHY node at exynos_ehci_get_phy?
>
> Ah, such workaround? I will check, but this will need to be done with 
> care, because have a side effect for other subsystems like regulators or 
> clocks.
>
> BTW, What's wrong with proper, full verification of USB device nodes?

Your approach so far doesn't address the actual problem of a conflict
between the generic USB DT bindings and those for the Exynos host
controller.  If you fix that, the validation issue goes away.

-- 
Måns Rullgård

  reply	other threads:[~2019-05-13 10:06 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20190507125630eucas1p1c5fd171a8dc2a6b8eb9dd317fe245f0c@eucas1p1.samsung.com>
2019-05-07 12:56 ` [PATCH] usb: core: verify devicetree nodes for disabled interfaces Marek Szyprowski
2019-05-07 13:24   ` Måns Rullgård
2019-05-08 10:14     ` Marek Szyprowski
     [not found]       ` <CGME20190508104442eucas1p2ebdffa348465f2c28177601014614853@eucas1p2.samsung.com>
2019-05-08 10:44         ` [PATCH v2] " Marek Szyprowski
2019-05-08 11:46           ` Måns Rullgård
2019-05-08 13:49             ` Marek Szyprowski
2019-05-08 15:27               ` Måns Rullgård
     [not found]                 ` <CGME20190509084827eucas1p294962744fe70745c50b69a5349b5de68@eucas1p2.samsung.com>
2019-05-09  8:47                   ` [PATCH v3] usb: core: verify devicetree nodes for USB devices Marek Szyprowski
2019-05-09 18:55                     ` Måns Rullgård
2019-05-10  3:10                       ` Peter Chen
2019-05-10  9:43                         ` Marek Szyprowski
2019-05-13  9:00                           ` Peter Chen
2019-05-13  9:07                             ` Marek Szyprowski
2019-05-13  9:23                               ` Peter Chen
2019-05-13 10:03                                 ` Marek Szyprowski
2019-05-13 10:06                                   ` Måns Rullgård [this message]
2019-05-17 11:15                                     ` Marek Szyprowski
2019-05-13 10:03                           ` Måns Rullgård
2019-05-17 11:18                             ` Marek Szyprowski
2019-05-09 19:04                     ` Tobias Jakobi

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