From: Greg KH <greg@kroah.com>
To: Christer Weinigel <christer@weinigel.se>
Cc: Andrew Lyon <andrew.lyon@gmail.com>, linux-kernel@vger.kernel.org
Subject: Re: Free Linux Driver Development!
Date: Sun, 4 Feb 2007 10:19:12 -0800 [thread overview]
Message-ID: <20070204181912.GA12379@kroah.com> (raw)
In-Reply-To: <m3y7neoxue.fsf@zoo.weinigel.se>
On Sun, Feb 04, 2007 at 02:29:13PM +0100, Christer Weinigel wrote:
> Greg KH <greg@kroah.com> writes:
>
> > Why would a userspace driver not work out for this. We already can
> > saturate the USB bus with a userspace program
>
> That is unfortunately not quite true. I have a (unfortunately
> proprietary) driver for a USB device that simply cannot be implemented
> in userspace. The USB device is a measurement device that pushes
> close to 800 kBytes/second of data through a FT245 chip. The
> measurement device does no flow control at all, it just presents a
> sample every 125 us to the FT245 and with only 256 bytes of buffer in
> the FT245 the only way to handle that is to have two URBs in flight at
> the same time, and I haven't found any way to do that in a robust and
> non-racey way from userspace.
People do that today just fine with multiple userspace urbs in flight
using usbfs directly. So it is possible and can be done.
If there are issues with the usbfs code to prevent you from doing this,
please let us know.
Or perhaps your device just needs to add some flow control to it :)
good luck,
greg k-h
next prev parent reply other threads:[~2007-02-04 18:20 UTC|newest]
Thread overview: 182+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-30 1:29 Free Linux Driver Development! Greg KH
2007-01-30 2:19 ` Rik van Riel
2007-01-30 2:23 ` Greg KH
2007-01-30 7:33 ` Bauke Jan Douma
2007-01-30 19:15 ` Greg KH
2007-01-30 20:42 ` Valdis.Kletnieks
2007-01-30 10:52 ` Jan Engelhardt
2007-01-30 19:14 ` Greg KH
2007-01-30 19:31 ` Jan Engelhardt
2007-01-30 19:46 ` Greg KH
2007-01-30 20:23 ` Diego Calleja
2007-01-30 20:39 ` Jan Engelhardt
2007-01-31 21:13 ` Jan-Benedict Glaw
2007-01-31 21:56 ` Willy Tarreau
2007-01-31 22:04 ` Jan-Benedict Glaw
2007-01-30 13:45 ` Florian Weimer
2007-01-30 19:12 ` Greg KH
2007-01-30 19:40 ` Florian Weimer
2007-01-30 19:47 ` Greg KH
2007-01-30 17:30 ` Manu Abraham
2007-01-30 19:11 ` Greg KH
2007-01-30 22:21 ` Manu Abraham
2007-01-30 19:33 ` Bill Davidsen
2007-01-30 19:55 ` Greg KH
2007-01-30 17:45 ` Roland Dreier
2007-01-30 17:55 ` Manu Abraham
2007-01-30 18:20 ` Jeff Garzik
2007-01-30 18:11 ` Jeff V. Merkey
2007-01-30 19:02 ` Roland Dreier
2007-01-30 19:36 ` Jeff Garzik
2007-01-30 19:10 ` Greg KH
2007-01-30 19:29 ` Roland Dreier
2007-01-30 19:46 ` Jeff Garzik
2007-01-30 21:38 ` Roland Dreier
2007-01-30 21:47 ` Greg KH
2007-01-30 22:00 ` Roland Dreier
2007-01-30 22:12 ` Jeff Garzik
2007-01-30 22:19 ` Roland Dreier
2007-01-30 22:39 ` John W. Linville
2007-01-30 22:23 ` Lennart Sorensen
2007-02-01 13:59 ` Erik Mouw
2007-02-01 14:45 ` Lennart Sorensen
2007-02-01 22:39 ` Erik Mouw
2007-02-01 15:46 ` Michael Buesch
2007-02-01 16:42 ` Lennart Sorensen
2007-02-01 17:48 ` Michael K. Edwards
2007-01-30 22:14 ` Dave Airlie
2007-01-30 22:24 ` Trent Waddington
2007-01-30 22:41 ` Jeff Garzik
2007-01-31 13:34 ` David Hollis
2007-01-31 17:56 ` Jan Engelhardt
2007-01-31 18:37 ` Bob Copeland
2007-02-01 5:52 ` Greg KH
2007-02-04 20:54 ` Bill Davidsen
2007-01-31 17:50 ` Jan Engelhardt
2007-01-31 17:55 ` Jeff Garzik
2007-01-31 17:58 ` alan
2007-01-31 18:29 ` Jan Engelhardt
2007-01-31 19:17 ` alan
2007-01-30 22:08 ` Jeff Garzik
2007-01-30 22:15 ` Roland Dreier
2007-01-30 23:01 ` Jeff Garzik
2007-01-30 22:19 ` Matthieu CASTET
2007-01-30 22:42 ` Jeff Garzik
2007-01-31 4:02 ` Andrey Borzenkov
2007-01-31 12:49 ` Alan
2007-01-31 18:37 ` Andrey Borzenkov
2007-01-30 23:03 ` Alan
2007-01-31 17:03 ` Eric Sandeen
2007-01-31 17:07 ` Jeff Garzik
2007-01-31 17:09 ` Eric Sandeen
2007-02-07 14:03 ` Tejun Heo
2007-02-07 18:40 ` Greg KH
2007-01-31 17:28 ` Alan
2007-01-30 19:54 ` Greg KH
2007-01-30 21:46 ` Roland Dreier
2007-01-30 22:27 ` Lennart Sorensen
2007-01-30 22:34 ` Jeff Garzik
2007-01-30 22:50 ` Roland Dreier
2007-01-30 23:05 ` Greg KH
2007-01-30 23:09 ` Jeff Garzik
2007-01-30 23:29 ` Roland Dreier
2007-01-30 23:45 ` Manu Abraham
2007-01-31 0:16 ` Jeff Garzik
2007-01-31 0:46 ` Greg KH
2007-01-31 1:07 ` Roland Dreier
2007-01-31 1:30 ` Greg KH
2007-02-07 10:30 ` Laurent Pinchart
2007-01-30 22:43 ` Alan
2007-01-30 19:52 ` Diego Calleja
2007-01-30 20:11 ` Greg KH
2007-01-31 1:13 ` Adrian Bunk
2007-01-31 1:19 ` Trent Waddington
2007-01-31 2:14 ` Adrian Bunk
2007-01-31 1:24 ` Greg KH
2007-01-31 2:11 ` Bartlomiej Zolnierkiewicz
2007-01-31 2:14 ` Adrian Bunk
2007-02-05 9:49 ` Stefan Seyfried
2007-02-06 13:37 ` Sunil Naidu
2007-02-06 14:57 ` Dave Jones
2007-02-06 16:30 ` Gene Heskett
2007-02-06 16:36 ` Gene Heskett
2007-02-06 21:14 ` Akemi Yagi
2007-02-06 22:15 ` floppy (Re: Free Linux Driver Development!, OT) Oleg Verych
2007-02-07 13:33 ` Free Linux Driver Development! Sunil Naidu
2007-02-07 13:50 ` Lennart Sorensen
2007-02-08 0:43 ` David Lang
2007-02-06 15:12 ` Bill Davidsen
2007-02-06 16:11 ` Stefan Seyfried
2007-01-31 10:08 ` Rewriting floppy.c was " Andi Kleen
2007-01-31 9:20 ` Jesper Juhl
2007-01-31 9:32 ` Trent Waddington
2007-01-31 9:34 ` Jesper Juhl
2007-01-31 16:18 ` Martin Seidl
2007-01-31 17:24 ` Adrian Bunk
2007-01-31 18:24 ` Jan Engelhardt
2007-01-31 18:58 ` Lennart Sorensen
2007-01-31 19:20 ` Jan Engelhardt
2007-01-31 21:46 ` Jan-Benedict Glaw
2007-02-01 13:12 ` Bartlomiej Zolnierkiewicz
2007-02-01 13:22 ` Jesper Juhl
2007-02-01 17:13 ` Al Viro
2007-01-31 17:41 ` Sergei Organov
2007-02-01 5:46 ` Greg KH
2007-02-01 14:22 ` Sergei Organov
2007-02-01 14:41 ` Alan
2007-01-30 19:08 ` Dmitri Vorobiev
2007-01-30 19:49 ` Greg KH
2007-01-30 20:15 ` Andrew Lyon
2007-01-30 20:30 ` Greg KH
2007-02-04 13:29 ` Christer Weinigel
2007-02-04 18:19 ` Greg KH [this message]
2007-02-04 21:33 ` Christer Weinigel
2007-01-31 2:27 ` Michael K. Edwards
2007-01-31 6:26 ` Greg KH
2007-01-31 6:48 ` Kumar Gala
2007-01-31 20:01 ` Michael K. Edwards
[not found] ` <355711.50750.qm@web36602.mail.mud.yahoo.com>
2007-02-04 18:20 ` Greg KH
2007-02-04 19:08 ` Miguel Ojeda
2007-02-05 8:13 ` Greg KH
2007-02-05 15:24 ` Jiri Slaby
2007-02-06 6:42 ` Greg KH
2007-02-06 13:35 ` Sunil Naidu
2007-02-06 17:01 ` Greg KH
2007-02-04 18:59 ` Pierre Ossman
2007-02-06 6:44 ` Greg KH
2007-02-06 8:29 ` Manu Abraham
2007-02-06 18:21 ` Greg KH
2007-02-07 7:12 ` Miguel Ojeda
2007-02-07 18:42 ` Greg KH
[not found] <fa.vy0GBdNvEFvgi9ipVzdiBp0FpjI@ifi.uio.no>
[not found] ` <fa.INRmyia9BGp5I+SBT3+o7eNe+vo@ifi.uio.no>
[not found] ` <fa.JOovioFiqyKNIa9g0QxNLn/pldw@ifi.uio.no>
[not found] ` <fa.f1ctPsEcBEc59B+Sd5oTTUfDmIs@ifi.uio.no>
[not found] ` <fa.OyKqe20gDjwobkBZicjVmJ5DPp8@ifi.uio.no>
[not found] ` <fa.T1Mpk9x9o81uajHKj9J8RE8yM2c@ifi.uio.no>
2007-01-30 23:35 ` Robert Hancock
-- strict thread matches above, loose matches on Subject: below --
2007-01-31 13:06 Nicolas Mailhot
2007-01-31 19:29 ` Francois Romieu
2007-01-31 19:54 ` Auke Kok
2007-01-31 21:33 ` Jan Engelhardt
2007-01-31 21:48 ` Trent Waddington
2007-01-31 20:09 ` Nicolas Mailhot
2007-01-31 20:12 ` Greg KH
2007-01-31 21:15 ` Nicolas Mailhot
2007-02-01 5:50 ` Greg KH
2007-01-31 22:06 ` Dave Jones
2007-01-31 22:08 ` Randy Dunlap
2007-01-31 23:00 ` Theodore Tso
2007-01-31 23:04 ` Randy Dunlap
2007-02-01 1:08 ` Mark Lord
2007-02-01 1:39 ` Lee Revell
2007-02-01 10:08 ` Jeff Garzik
2007-01-31 23:44 ` Greg KH
2007-02-01 0:07 ` Trent Waddington
2007-02-01 1:58 ` Greg KH
2007-02-01 8:40 ` Nicolas Mailhot
2007-02-01 9:03 ` Trent Waddington
2007-02-01 9:22 ` Nicolas Mailhot
2007-02-01 9:34 ` Trent Waddington
2007-01-31 23:59 ` Lee Revell
2007-02-01 11:43 ` Jan Engelhardt
2007-02-14 12:00 ` Pavel Machek
2007-02-02 4:54 Christoph Bartelmus
2007-02-04 6:26 Larry Finger
2007-02-04 10:36 ` Michael Buesch
2007-02-04 21:37 devzero
2007-02-04 23:04 ` Oleg Verych
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