[openib-general] [PATCH] mthca: Test interrupts during initialization

[Michael S. Tsirkin]

Hi, Roland.
Quoting r. Michael S. Tsirkin (mst at mellanox.co.il) "Re: [openib-general] [PATCH] mthca: Test interrupts during initialization":
> Hello!
> Quoting r. Roland Dreier (roland at topspin.com) "Re: [openib-general] [PATCH] mthca: Test interrupts during initialization":
> >     Michael> If mthca could downgrade gracefully to regular
> >     Michael> interrupts, the default for msi-x could be changed to 1?
> > 
> > Possibly (although it depends on the precise MSI-X failure mode).
> > Also I seem to remember some problems with changing the PCI header
> > (ie to enable/disable MSI-X) after SYS_EN, although I can't remember
> > exactly what the issue was.
> > 
> >  - R.
> 
> You asked the right person :)
> You cant do it on tavor, but it will be fine if you
> close everything and do system disable.
> mst

I stand corrected.

To disable MSI, it is sufficient to close all EQs,
perform the appropriate pci configuration transaction to disable MSI,
and then re-create the EQs with interrupt value instead of the MSI value.

You do not have to go through system disable.

By the way, if you plan to do it, I think you also may want to check
the FW revision since older FW revisions had issues with MSI or MSIX.

MST