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]
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