Re: Is it possible to issue device reset to PMC PM8388 expander using sg3_utils or smp_utils?

[Jeff Johnson <jeff.johnson@aeoncomputing.com>]

On 12/9/10 10:59 AM, James Bottomley wrote:
> On Thu, 2010-12-09 at 10:41 -0800, Jeff Johnson wrote:
>> Greetings,
>>
>> Is it possible to issue a low level device reset to a PMC-Sierra PM8388
>> 24x3G SAS expander using either sg3_utils or smp_utils?
>>
>> I am able to enumerate and read the status of the phys on the PM8388,
>> read end device information, etc. I tried sg_reset and it does a bus
>> reset but not an expander reset.
>>
>> Technical documentation on the PM8388 is not readily available so I do
>> not know if it has a mode select bit or other special method to get the
>> expander to reset itself.
>>
>> I am looking for an inband method to reset the expander to clear a
>> condition where some phys in a wide connection fail to link. A power
>> cycle clears the condition and I am looking to mimic a power cycle by
>> bouncing the expander at the lowest level possible via the SAS host
>> connection.
> There's no protocol defined way to reset an expander using SMP
> functions, so it's not really possible to do it in-band.  It's sort of
> like asking if there's an ethernet packet you can send to a switch to
> cause it to reset.

Now that would be fun.... =)

> If the wide port isn't forming, you could try doing a hard reset of all
> the phys in the port.

I have tried that from the hba side using lsiutil and it did not clear 
the condition. I will try the expander phys and see if the result is any 
better.

When the wide port fails to form the error I see on the three phys that 
fail to link (from the PM8388 exp side) is "sspl reg trigger error"

--Jeff