Re: Suspending SCSI devices and buses

[Nathan Bryant <nbryant@optonline.net>]

Alan Stern wrote:
> How does a host driver tell the SCSI core that an adapter is being 
> suspended (and hence the core needs to suspend all the devices attached to 
> that adapter)?  Ditto for resume.

For devices, this should be handled by the applicable scsi_driver - 
sd.c, etc. I posted a patch for this to the mailing list a week or two 
ago, check the list archives.

> 
> There doesn't appear to be any way to do it.  The scsi_bus_type and 
> various driver structures don't contain a "suspend" entry.

Correct, the midlayer doesn't quite support this yet, but my patch 
should do the most important bits if somebody would be kind enough to 
merge it... As a quick summary, first we need to quiesce the child 
devices and synchronize their caches, then the LLD just needs to handle 
flushing any remaining in-flight DMA transactions.

I also have an example patch to do this for the aic7xxx LLD. Which you 
can also grab from the list archives.

Nathan

> 
> Alan Stern
> 
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