From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wolfgang Grandegger <wg@grandegger.com>
Subject: Re: Dual SJA1000 can controllers on SMP system.
Date: Mon, 17 Jun 2013 21:34:42 +0200
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References: <c2744427f1624d26950ca030d4dff1c6@s75.digisrv.net> <51BDB1ED.1040603@grandegger.com> <51BEA863.1040704@hostmobility.com> <51BEB849.3020409@pengutronix.de> <51BF132B.3020705@hostmobility.com> <51BF193B.1030307@pengutronix.de> <51BF5A38.3080001@hostmobility.com>
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To: Mirza Krak <mirza.krak@hostmobility.com>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>, linux-can@vger.kernel.org, Rickard Gustafsson <rickard.gustafsson@hostmobility.com>, Tord Andersson <tord.andersson@endian.se>

On 06/17/2013 08:49 PM, Mirza Krak wrote:
> Thank you Marc for your patch. We  applied it but it did not solve our
> problem.
> 
> Wolfgang suggested defining a lock common for all devices:
> 
>  static DEFINE_SPINLOCK(snor_bus_lock);
> 
> Which I applied and now it seems to work perfectly. Thank you for your
> help.
> 
> Should I blame the hardware driver? :)

Even if there is a separate set of registers for each device, they can
obviously not be accessed concurrently. Well, you can say it's a
hardware feature, but a stupid and inefficient one.

Wolfgang.