netdev - Re: [PATCH 2/2 v2] sierra_net: fix issues with SYNC/RESTART messages and interrupt pipe setup

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Message-ID: <87ip655eqw.fsf@nemi.mork.no>
Date:	Wed, 06 Feb 2013 22:11:51 +0100
From:	Bjørn Mork <bjorn@...k.no>
To:	Dan Williams <dcbw@...hat.com>
Cc:	Oliver Neukum <oliver@...kum.org>,
	Elina Pasheva <epasheva@...rrawireless.com>,
	netdev@...r.kernel.org, linux-usb@...r.kernel.org,
	Rory Filer <rfiler@...rrawireless.com>,
	Phil Sutter <phil@....cc>
Subject: Re: [PATCH 2/2 v2] sierra_net: fix issues with SYNC/RESTART messages and interrupt pipe setup

Dan Williams <dcbw@...hat.com> writes:

> As part of the initialization sequence, the driver sends a SYNC message
> via the control pipe to the firmware, which appears to request a
> firmware restart.  The firmware responds with an indication via the
> interrupt pipe set up by usbnet.  If the driver does not receive a
> RESTART indication within a certain amount of time, it will periodically
> send additional SYNC messages until it receives the RESTART indication.
>
> Unfortunately, the interrupt URB is only submitted while the netdev
> is open, which is usually not the case during initialization, and thus
> the firmware's RESTART indication is lost.  So the driver continues
> sending SYNC messages, and eventually the firmware crashes when it
> receives too many.  This leads to a wedged netdev.
>
> To ensure the firmware's RESTART indications can be received by the
> driver, request that usbnet keep the interrupt URB active via
> FLAG_INTR_ALWAYS.
>
> Second, move the code that sends the SYNC message out of the
> bind() hook and after usbnet_probe() to ensure the interrupt URB
> is set up before trying to use it.

Given this description I am wondering if you couldn't just move the
whole SYNC thing to a new reset() hook, using some private flag to make
sure it only runs once?  Does it really need to start at probe time?


Bjørn


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