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Message-ID: <1270681636.6401.5.camel@Linuxdev4-laptop>
Date: Wed, 7 Apr 2010 16:07:16 -0700
From: Elina Pasheva <epasheva@...rrawireless.com>
To: David Brownell <david-b@...bell.net>
CC: Rory Filer <rfiler@...rraWireless.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
David Miller <davem@...emloft.net>
Subject: Re: [PATCH 1/1] NET: usb: Adding URB_ZERO_PACKET flag to usbnet.c
On Wed, 2010-04-07 at 14:14 -0700, David Brownell wrote:
> On Tuesday 06 April 2010, you wrote:
> Recall that the reason to avoid sending zero length packts
> (ZLPs) is that many systems don't cope well with them...
>
> The ""don't cope well" can be at the hardware level,
> or drivers not limited to device firmware. I've seen
> the failures be very context-dependent .... as in, one
> standalone ZLP might work, but mix it in with back-to-back
> delivery of other packets and trouble ensues...
>
> In short, it's hard to know which combinations of
> hardware an firmware would need it .... versus which
> ones it would break.
>
> ... and thus risky to try sending ZLPs through systems
> shere for many years) we've carefully avoided doing that.
>
>
> - Dave
>
Hi Dave,
Nice to hear your opinion on this matter. Are you recommending our patch
be retracted? If so, we can look at other ways to fix the problem when a
zero length packet is missing.
Regards,
Elina
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