Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <d1a5f149-50a1-49fc-9a6d-eceffa23311b@gmx.com>
Date:   Tue, 30 Aug 2022 15:56:59 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.13.0
Subject: Re: [PATCH] usb: add quirks for Lenovo OneLink+ Dock
Content-Language: en-US
To:     Oliver Neukum <oneukum@suse.com>, gregkh@linuxfoundation.org,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20220824160946.10128-1-jflf_kernel@gmx.com>
 <31aeee3c-f4f1-16a8-272b-96da5d4a565e@suse.com>
From:   jflf_kernel@gmx.com
In-Reply-To: <31aeee3c-f4f1-16a8-272b-96da5d4a565e@suse.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
Precedence: bulk


On 30/08/2022 13.54, Oliver Neukum wrote:
> On 24.08.22 18:09, JFLF wrote:
>
>> By process of elimination the controllers themselves were identified as
>> the cause of the problem. Through trial and error the issue was solved
>> by using USB_QUIRK_RESET_RESUME for both chips.
>
> Hi,
>
>
> aside from the aspects of getting this properly signed off and merged,
> this opens up a question. What does resetting a hub do to its children?
> That is if the request to wake up comes from a child, do we
>
> a) lose state in the child?
> b) retain the knowledge which port requested the wakeup?
>
> How far has this patch been tested?
>
> 	Regards
> 		Oliver


Hi Oliver,

Partial answer for now: I have been using those quirks via the kernel comm=
and line for about a year now. I have been meaning to send in the patch lo=
ng ago, but kept forgetting about it.

I agree that USB_QUIRK_RESET_RESUME seems fishy with a hub. It's pretty mu=
ch the last quirk I tried, and the only one that worked. I can't say I und=
erstand what it does exactly. The hubs themselves don't seem to reset (or =
at least not fully), as there is no re-enumeration of existing children.

I have not experienced a single problem or side effect since using those q=
uirks. I use a mix of USB 2.0 and 3.0 devices, some bus- and some self-pow=
ered, some permanently connected (including ethernet and audio in the hub =
itself) and some not.

Thanks!
JF