From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oliver Neukum Subject: Re: [PATCH] net: usb: allow MTU that is a multiple of USB packet size Date: Thu, 07 May 2015 13:07:37 +0200 Message-ID: <1430996857.30151.8.camel@suse.de> References: <1430992159-27783-1-git-send-email-ruslan.bilovol@gmail.com> <1430993477.30151.6.camel@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" To: Ruslan Bilovol Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, 2015-05-07 at 13:51 +0300, Ruslan Bilovol wrote: > Hi Oliver, > > On Thu, May 7, 2015 at 1:11 PM, Oliver Neukum wrote: > > On Thu, 2015-05-07 at 12:49 +0300, Ruslan Bilovol wrote: > >> Current usbnet driver rejects setting MTU that is a multiple > >> of USB endpoint's wMaxPacketSize size. However, it may only > >> lead to possible performance degradation but is not so > >> critical that its using should be prohibited. So allow it > >> but also warn user about possible issue. > > > > We have reports about devices reacting badly to ZLPs. > > Unless you have a compelling reasons for this change > > I have to reject it. > > What devices do you mean here: USB network adapters or USB host controllers? The network adapters > If it's just network adapters, then we can create some kind of quirk handling > for them and do not disable this functionality just because some buggy device > can't work with it. No. They are too many. > My device works fine with ZLPs so I want to use this particular MTU under Linux > like I do it under other operation systems. We can have a white list, but the general case is just too dangerous. Sorry Oliver