From: "Sid Spry" <sid@aeam.us>
To: "Claus Stovgaard" <claus.stovgaard@gmail.com>,
"Alan Stern" <stern@rowland.harvard.edu>
Cc: "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>
Subject: Re: Options for forcing dwc3 gadget to only accept superspeed
Date: Tue, 12 May 2020 23:47:27 -0500 [thread overview]
Message-ID: <ba5a11fe-90a6-48c2-8da1-66076e52c6b4@www.fastmail.com> (raw)
In-Reply-To: <e89456b5-20db-48c1-814b-075e84ca8b8b@www.fastmail.com>
Hello again, I'm terribly sorry for the double post. Claus, you might try detecting the speed of the connection and re-enumerating if necessary. It would avoid noncompliance with the spec and is probably the easiest option.
Unsure of how this would be done with a C manifestation of functionfs code but echoing "" to the UDC pseudofile under /sys/kernel/config/usb_gadget/${your_gadget} will allow you to set everything up again and reenumerate.
On Tue, May 12, 2020, at 11:43 PM, Sid Spry wrote:
> Have you tried only providing a SS configuration? If that fails for some reason I suspect the next course of action would be to see why, and patch the driver so it does not.
>
> Out of curiosity, which SoC are you using?
>
> On Tue, May 12, 2020, at 3:08 PM, Claus Stovgaard wrote:
> > On tir, 2020-05-12 at 15:52 -0400, Alan Stern wrote:
> > > On Tue, May 12, 2020 at 09:25:38PM +0200, Claus Stovgaard wrote:
> > > >
> > > > In a certain scenario I would like to force the dwc3 to only
> > > > connect
> > > > via superspeed and not fall back to USB2.
> > > >
> > > > What options exist for forcing the dwc3 to keep retry?
> > >
> > > The USB-3 spec forbids devices from operating only at SuperSpeed.
> > > Devices must be able to connect at high speed, although possibly
> > > with
> > > reduced functionality.
> > >
> > > Alan Stern
> > >
> >
> > I understand the requirement from the USB 3 specification. Though in
> > the scenario for this specific device, it is not about comply with the
> > USB 3 specification, but my question is rather what options I have for
> > not comply with the specification here, and then force retry of USB 3,
> > using the dwc3 as device.
> >
> > The device is in a fixed mounting with a fixed host. Sometimes when the
> > host and device is powered up, it ends in high-speed instead of super-
> > speed. I would like the option for "I will not be compliant with USB,
> > but rather retry super-speed".
> >
> > Regards
> > Claus
> >
> >
next prev parent reply other threads:[~2020-05-13 4:48 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-12 19:25 Options for forcing dwc3 gadget to only accept superspeed Claus Stovgaard
2020-05-12 19:52 ` Alan Stern
2020-05-12 20:08 ` Claus Stovgaard
2020-05-13 4:43 ` Sid Spry
2020-05-13 4:47 ` Sid Spry [this message]
2020-05-14 7:06 ` Claus Stovgaard
2020-05-13 7:34 ` Felipe Balbi
2020-05-14 8:53 ` Claus Stovgaard
2020-05-14 9:34 ` Felipe Balbi
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ba5a11fe-90a6-48c2-8da1-66076e52c6b4@www.fastmail.com \
--to=sid@aeam.us \
--cc=claus.stovgaard@gmail.com \
--cc=linux-usb@vger.kernel.org \
--cc=stern@rowland.harvard.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.