RE: [PATCH 1/2] I/OAT: Add watchdog/reset functionality to ioatdma driver

From: Sosnowski, Maciej
Date: Fri Jul 18 2008 - 12:06:25 EST

Brice Goglin wrote:
> 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 ?

Yes, it is transparent.
The driver should take care of all the descriptors
that have not been served before the reset.

>> 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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