Linux-USB Archive on lore.kernel.org
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From: Sam Bingner <sam@bingner.com>
To: "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>,
	Martin Habets <mhabets@solarflare.com>,
	Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
	Shannon Nelson <snelson@pensando.io>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Matti Vuorela <matti.vuorela@bitfactor.fi>,
	Jakub Kicinski <kuba@kernel.org>,
	"Yves-Alexis Perez" <corsac@corsac.net>
Subject: Re: [PATCH] usbnet: ipheth: fix connectivity with iOS 14
Date: Sun, 21 Feb 2021 10:42:44 +0000
Message-ID: <370902e520c44890a44cb5dd0cb1595f@bingner.com> (raw)

There seems to be a problem with this patch:

Whenever the iPhone sends a packet to the tethered device that is 1500 bytes long, it gets the error "ipheth 1-1:4.2: ipheth_rcvbulk_callback: urb status: -79" on the connected device and stops passing traffic.  I am able to bring it back up by shutting and unshutting the interface, but the same thing happens very quickly.   I noticed that this patch dropped the max USB packet size from 1516 to 1514 bytes, so I decided to try lowering the MTU to 1498; this made the connection reliable and no more errors occurred.

It appears to me that the iPhone is still sending out 1516 bytes over USB for a 1500 byte packet and this patch makes USB abort when that happens?  I could duplicate reliably by sending a ping from the iphone (ping -s 1472) to the connected device, or vice versa as the reply would then break it.

I apologize if this reply doesn't end up where it should - I tried to reply to the last message in this thread but I wasn't actually *on* the thread so I had to just build it as much as possible myself.

Sam

             reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-21 10:42 Sam Bingner [this message]
2021-02-22 12:09 ` Oliver Neukum
  -- strict thread matches above, loose matches on Subject: below --
2020-09-27 14:14 /net/usb/ipheth.c incompatibility with Apple " Kiran
2020-11-19 17:24 ` [PATCH] usbnet: ipheth: fix connectivity with " Yves-Alexis Perez
2020-11-20  9:15   ` Sergei Shtylyov
2020-11-20 16:56     ` Yves-Alexis Perez
2020-11-21 22:03   ` Jakub Kicinski
2020-11-24 10:41     ` Yves-Alexis Perez
2020-11-24 16:39       ` Jakub Kicinski

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