Created attachment 285817 [details]
Power-On-Reset Prevents Successful Receive Diagnostics Command

Overview:

When booting an SES device connected to an ATTO SAS HBA, the SES module issues a 'Receive Diagnostics' command that fails with check condition power-on-reset and is not retried by the SES module.

Interestingly, when booting an SES device connected to an LSI SAS HBA, the Receive Diagnostics succeeds due to LSI issuing a 'Mode Sense' command prior to the SES module sending the 'Receive Diagnostics' that clears the check condition power-on-reset.

Us (ATTO) does not want to have to issue a command to clear the check condition power-on-reset unless we must. There is no spec that states this is what must happen and seems to be a case that the SES module should handle.


Steps to Reproduce:

With an ATTO SAS HBA:
Connect an SES device to an ATTO SAS HBA, then power on the SES device. 

With an LSI SAS HBA:
I was able to reproduce this issue with an LSI SAS HBA and other SAS HBAs by unloading the SES module, issuing a target reset to the SES device, then re-loading the SES module.


Actual Results:

In the system log you will see

[  953.809858] scsi 7:0:0:0: Power-on or device reset occurred
[  953.809891] scsi 7:0:0:0: Failed to get diagnostic page 0x1
[  953.809931] scsi 7:0:0:0: Failed to bind enclosure -19

This can also be observed in the "sas_poweron_atto.scs" SAS trace.


Expected Results:

The Receive Diagnostics command to succeed and no error logged to the system log.

This can also be observed in a SAS trace of an SES device connected to an LSI HBA, where the 'Receive Diagnostics' command succeeds due to the check condition power-on-reset being cleared by the 'Mode Sense' command issued prior to the 'Receive Diagnostics'. (Trace can be provided upon request).


Additional Information:

It appears that I cannot attach SAS traces from both ATTO and LSI devices, so I have attached the trace while connected to an ATTO SAS HBA that clearly exhibits the error. If both traces are needed, I can provide them by a different means.