linux-kernel - Re: [PATCH] rt2x00: Endless loop on hub port power down

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Date:	Fri, 4 Apr 2014 16:13:21 +0200
From:	Stanislaw Gruszka <sgruszka@...hat.com>
To:	Richard Genoud <richard.genoud@...il.com>
Cc:	Ivo van Doorn <IvDoorn@...il.com>,
	Gertjan van Wingerde <gwingerde@...il.com>,
	Helmut Schaa <helmut.schaa@...glemail.com>,
	"John W. Linville" <linville@...driver.com>,
	linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rt2x00: Endless loop on hub port power down

On Fri, Apr 04, 2014 at 11:58:26AM +0200, Richard Genoud wrote:
> On 04/04/2014 10:04, Stanislaw Gruszka wrote:
> > On Thu, Apr 03, 2014 at 04:48:56PM +0200, Richard Genoud wrote:
> >> I've met an endless (or at least very long) loop if I power down the usb
> >> port on witch a usb wifi key is plugged.
> >> (Ok, it's not very smart to power down a usb port when a usb key is in
> >> used... but still, I think that should not lead to an endless loop).
> >>
> >> I have a lot of:
> >> ieee80211 phy1: rt2x00usb_vendor_request: Error - Vendor Request 0x07 failed for offset 0x0438 with error -71
> >>
> >> (-71==-EPROTO)
> >>
> >> How to reproduce:
> >> - plug an usb wifi key
> >> - ip link set wlan0 up
> >> - hub-ctrl -b usb_bus -d usb_device -P usb_port -p 0
> >>
> >> hub-ctrl source: https://github.com/codazoda/hub-ctrl.c/blob/master/hub-ctrl.c
> >>
> >> The following patch prevents the endless loop, but I'm really not sure
> >> that The Right Way To Do It (R)
> > 
> > If device disappear, we should get -ENODEV status, why we get -EPROTO ?
> 
> I trace it down, and the EPROTO status comes from ctx.status (returned from usb_start_wait_urb() in drivers/usb/core/message.c)
> And, in my case, the ctx.status is set to EPROTO in qtd_copy_status() ( drivers/usb/host/ehci-q.c )
> in the code:
> } else if (token & QTD_STS_XACT) {
> 	/* timeout, bad CRC, wrong PID, etc */
> 	ehci_dbg(ehci, "devpath %s ep%d%s 3strikes\n",
> 		urb->dev->devpath,
> 		usb_pipeendpoint(urb->pipe),
> 		usb_pipein(urb->pipe) ? "in" : "out");
> 	status = -EPROTO;
> 
> enabling this log, I get:
> atmel-ehci 700000.ehci: devpath 2.1 ep1in 3strikes
> atmel-ehci 700000.ehci: devpath 2.1 ep0in 3strikes
> atmel-ehci 700000.ehci: devpath 2.1 ep1in 3strikes
> atmel-ehci 700000.ehci: devpath 2.1 ep0in 3strikes
> ieee80211 phy0: rt2800usb_tx_sta_fifo_read_completed: Warning - TX status read failed -71

Thanks, ehci driver behaviour seems to be fine. Could you check if updating
rt2800 firmware (I assume you have some RT2800 usb dongle) change the situation,
i.e. we stop getting -EPROTO errors. To install new firmware, you can download
rt2870.bin blob from:
http://rt2x00.serialmonkey.com/pipermail/users_rt2x00.serialmonkey.com/2013-January/005610.html
and need to replace /lib/firmware/rt2870.bin file.

Stanislaw
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