From: Johannes Stezenbach <js@sig21.net>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Markus Rechberger <mrechberger@gmail.com>,
Greg KH <gregkh@suse.de>, USB list <linux-usb@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [Patch] Increase USBFS Bulk Transfer size
Date: Mon, 17 Oct 2011 20:11:18 +0200 [thread overview]
Message-ID: <20111017181117.GA17422@sig21.net> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1110151459030.15129-100000@netrider.rowland.org>
On Sat, Oct 15, 2011 at 03:04:28PM -0400, Alan Stern wrote:
> On Sat, 15 Oct 2011, Johannes Stezenbach wrote:
>
> > It would make a difference if the
> > device violated the spec and sent 188 byte packets. However, the
> > spec says a short packet terminates the transfer. But I wonder
> > if this is really the case?
>
> The device does not send short packets. If it did, the 24064-byte
> transfers would end early.
Re-reading the USB-2.0 standard, a short packet which terminates
the transfer is defined by packet_size < wMaxPacketSize,
not by packet_size < 512.
Thus wMaxPacketSize == 188 (or 2*188) might be possible.
There is a comment in linux/drivers/usb/host/ehci-q.c:
/* The USB spec says that high speed bulk endpoints
* always use 512 byte maxpacket. But some device
* vendors decided to ignore that, and MSFT is happy
* to help them do so. So now people expect to use
* such nonconformant devices with Linux too; sigh.
*/
Maybe we should look at the descriptors?
Johannes
next prev parent reply other threads:[~2011-10-17 18:11 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-12 12:36 [Patch] Increase USBFS Bulk Transfer size Markus Rechberger
2011-10-12 12:46 ` Markus Rechberger
2011-10-12 13:48 ` Sergei Shtylyov
2011-10-12 14:17 ` Greg KH
2011-10-12 16:59 ` Markus Rechberger
2011-10-12 20:33 ` Greg KH
2011-10-12 21:48 ` Markus Rechberger
2011-10-12 22:09 ` Markus Rechberger
2011-10-13 4:03 ` Manu Abraham
2011-10-13 4:59 ` Markus Rechberger
2011-10-13 5:46 ` Manu Abraham
2011-10-13 8:37 ` Markus Rechberger
2011-10-13 9:29 ` Markus Rechberger
2011-10-16 9:22 ` James Courtier-Dutton
2011-10-13 9:34 ` Manu Abraham
2011-10-13 9:39 ` Markus Rechberger
2011-10-13 14:58 ` Alan Stern
2011-10-13 15:19 ` Markus Rechberger
2011-10-13 16:01 ` Chris Friesen
2011-10-13 16:12 ` Markus Rechberger
2011-10-13 16:25 ` Chris Friesen
2011-10-13 18:27 ` Markus Rechberger
2011-10-13 20:07 ` Alan Stern
2011-10-13 20:17 ` Markus Rechberger
2011-10-13 18:21 ` Alan Stern
2011-10-13 19:05 ` Alan Cox
2011-10-14 19:21 ` Johannes Stezenbach
2011-10-14 20:19 ` Alan Stern
2011-10-14 22:45 ` Johannes Stezenbach
2011-10-15 11:45 ` Markus Rechberger
2011-10-15 17:47 ` Valdis.Kletnieks
2011-10-15 19:08 ` Alan Stern
2011-10-15 19:04 ` Alan Stern
2011-10-16 9:10 ` Johannes Stezenbach
2011-10-16 14:18 ` Alan Stern
2011-10-17 18:11 ` Johannes Stezenbach [this message]
2011-10-17 18:22 ` Alan Stern
[not found] ` <CAAMvbhFNTQeuJBgsDB9Y5ODc_b2O0X=oP_3uwRpWUREFS9qufA@mail.gmail.com>
2011-10-14 2:47 ` Markus Rechberger
2011-10-14 3:42 ` Markus Rechberger
2011-10-14 3:48 ` Markus Rechberger
2011-10-14 5:47 ` Valdis.Kletnieks
2011-10-14 6:23 ` Markus Rechberger
2011-10-14 8:51 ` James Courtier-Dutton
2011-10-14 15:38 ` Markus Rechberger
2011-10-14 14:05 ` Alan Stern
2011-10-14 14:33 ` Greg KH
2011-11-07 18:52 ` Sarah Sharp
2011-11-07 19:12 ` Alan Stern
2011-11-07 20:18 ` Sarah Sharp
2011-11-07 20:37 ` Brink, Peter
2011-11-07 20:53 ` Alan Stern
2011-11-07 21:49 ` Greg KH
2011-11-07 23:07 ` Sarah Sharp
2011-11-08 1:44 ` Alan Stern
2011-11-07 19:16 ` Tim Vlaar
2011-11-07 19:55 ` Alan Stern
2011-11-07 20:13 ` Tim Vlaar
2011-10-17 18:38 ` Alan Stern
2011-10-17 19:07 ` Markus Rechberger
2011-10-12 18:00 ` Mihai Moldovan
2011-10-12 20:36 ` Greg KH
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