From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brownell Subject: Re: [PATCH 1/1] NET: usb: Adding URB_ZERO_PACKET flag to usbnet.c Date: Wed, 7 Apr 2010 14:14:33 -0700 Message-ID: <201004071414.33917.david-b@pacbell.net> References: <1270599787.8900.8.camel@Linuxdev4-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: rfiler-ywE8TTl5eJHWpu6QEFMNjNBPR1lH4CV8@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, David Miller To: Elina Pasheva Return-path: In-Reply-To: <1270599787.8900.8.camel@Linuxdev4-laptop> Content-Disposition: inline Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org 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 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html