linux-kernel - Re: [PATCH 1/2] I/OAT: Add watchdog/reset functionality to ioatdma driver

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Date:	Mon, 14 Jul 2008 16:17:40 +0200
From:	Brice Goglin <Brice.Goglin@...ia.fr>
To:	Maciej Sosnowski <maciej.sosnowski@...el.com>
CC:	dan.j.williams@...el.com, shannon.nelson@...el.com,
	linux-kernel@...r.kernel.org, net-dev@...r.kernel.org
Subject: Re: [PATCH 1/2] I/OAT: Add watchdog/reset functionality to ioatdma
 driver

Maciej Sosnowski wrote:
> Due to occasional DMA channel hangs observed for I/OAT versions 1.2 and 2.0
> a watchdog has been introduced to check every 2 seconds
> if all channels progress normally.
> If stuck channel is detected, driver resets it.
> The reset is done in two parts. The second part is scheduled 
> by the first one to reinitialize the channel after the restart.
>   

Is all this transparent to the caller? Are you reposting all copies to
the hardware after the reset? Or are we going to get some DMA_ERROR
return values ?

> Sleep time in self_test has been increased to 10ms
> since in some cases 1ms appeared not to be enough

Thanks Maciej, this helps a lot here.

Brice

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