From: Oliver Neukum <oliver@neukum.org>
To: David Laight <David.Laight@ACULAB.COM>
Cc: netdev@vger.kernel.org, Ming Lei <ming.lei@canonical.com>
Subject: Re: usbnet transmit path problems
Date: Wed, 11 Sep 2013 12:11:52 +0200 [thread overview]
Message-ID: <1378894312.28160.15.camel@linux-fkkt.site> (raw)
In-Reply-To: <AE90C24D6B3A694183C094C60CF0A2F6026B7325@saturn3.aculab.com>
On Wed, 2013-09-11 at 10:10 +0100, David Laight wrote:
> I've been looking at the code in drivers/net/usb/usbnet.c that
> processes tx data after the tx_fixup() function has run.
>
> The code currently looks like:
> 1) I can't see where skb_linearize() gets called if 'can_dma_sg' is unset.
That is the job of subdrivers.
> 2) If 'length % dev->maxpacket == 0' for a multi-fragment packet then
> the extra byte isn't added correctly (the code probably falls off
> the end of the scatter-gather list).
Indeed. Ming Lei, should usbnet handle this in the sg case or better
leave it to the subdriver you introduced this for?
> 4) I read that USB3 has a different scheme for terminating bulk data
> that is a multiple of the packet size.
> Does this mean that the pad byte isn't needed for USB3?
> (Or are USB3 controllers/targets just as buggy?)
We don't have enough examples to tell.
Regards
Oliver
next prev parent reply other threads:[~2013-09-11 10:11 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-11 9:10 usbnet transmit path problems David Laight
2013-09-11 10:11 ` Oliver Neukum [this message]
2013-09-11 11:34 ` Ming Lei
2013-09-11 12:56 ` David Laight
2013-09-11 15:11 ` Ming Lei
[not found] ` <CACVXFVN6ZHLesrsMVNMWrikRs1mMbk=aZD9qZybNn1gB7aFTZQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-09-11 16:05 ` David Laight
2013-09-12 1:56 ` Ming Lei
[not found] ` <CACVXFVNrbeEthBH0vGKN2gymoSwu3jTkcGicKNU1-Oez8bNhvg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-09-16 8:13 ` Oliver Neukum
[not found] ` <1379319193.15916.1.camel-B2T3B9s34ElbnMAlSieJcQ@public.gmane.org>
2013-09-16 12:38 ` Ming Lei
2013-09-11 13:00 ` David Laight
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