From: Johan Hovold <johan@kernel.org>
To: Steve Markgraf <steve@steve-m.de>
Cc: Johan Hovold <johan@kernel.org>, linux-usb@vger.kernel.org
Subject: Re: Regression in 5.5.0-rc6 for FL2000 USB 3.0 to VGA adapter
Date: Sun, 19 Jan 2020 16:15:19 +0100 [thread overview]
Message-ID: <20200119151519.GZ2301@localhost> (raw)
In-Reply-To: <734d9503-29ef-2fa0-5df8-6ef5701d3d61@steve-m.de>
On Sun, Jan 19, 2020 at 03:48:32PM +0100, Steve Markgraf wrote:
> Hi Johan,
>
> On 19.01.20 14:58, Johan Hovold wrote:
> > I just took a quick look at the libosmo-fl2k code and it appears that
> > you claim both interfaces but never set alternate setting 1 for
> > interface 0, which would enable those endpoints.
> >
> > Could you see if that's all that's needed to get your application
> > working again?
>
> Yes, you are right, I had another look at it today and tried exactly
> that, and it's working now with altsetting 1 of interface 0.
> I will push a change to osmo-fl2k shortly.
That's good to hear, thanks for confirming.
> There is also an out-of-tree kernel driver that makes use of this
> device, and might even need interface 1, but I haven't verified this so
> far:
>
> https://github.com/FrescoLogic/FL2000
I'm afraid we don't care much about out-of-tree kernel drivers.
> The question is if there are other devices out there where there are
> duplicate endpoints on different interfaces. The spec clearly states
> that this is forbidden, but the USBx0CV Chapter 9 tests do not test for
> this and pass just fine, so I assume the FL2000 will not be the only
> device in the market where this mistake has been made.
That's a valid concern, but the problem is that USB core cannot really
handle such devices currently. If we get a flood of reports about this
we may have to reconsider how best to deal with them however.
Johan
prev parent reply other threads:[~2020-01-19 15:15 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-18 23:52 Regression in 5.5.0-rc6 for FL2000 USB 3.0 to VGA adapter Steve Markgraf
2020-01-19 12:58 ` Greg KH
2020-01-19 12:59 ` Greg KH
2020-01-19 13:58 ` Johan Hovold
2020-01-19 14:48 ` Steve Markgraf
2020-01-19 15:15 ` Johan Hovold [this message]
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=20200119151519.GZ2301@localhost \
--to=johan@kernel.org \
--cc=linux-usb@vger.kernel.org \
--cc=steve@steve-m.de \
/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.