On Tue, Oct 01, 2013 at 05:51:33PM +1000, Michael Ellerman wrote: > The disadvantage is that any restriction imposed on us above the quota > can only be reported as an error from pci_enable_msix(). > > The quota code, called from pci_get_msix_limit(), can only do so much to > interogate firmware about the limitations. The ultimate way to check if > firmware will give us enough MSIs is to try and allocate them. But we > can't do that from pci_get_msix_limit() because the driver is not asking > us to enable MSIs, just query them. If things are this way then pci_enable_msix() already exposed to this problem internally on pSeries. I see that even successful quota checks in rtas_msi_check_device() and rtas_setup_msi_irqs() do not guarantee (as you say) that firmware will give enough MSIs. Hence, pci_enable_msix() might fail even though the its quota checks succeeded. Therefore, nothing will really change if we make pci_get_msix_limit() check quota and hope the follow-up call to pci_enable_msix() succeeded. (Of course, we could allocate-deallocate MSIs at check time, but I think it is an overkill). > You'll also need to add another arch hook, for the quota check, and > we'll have to add it to our per-platform indirection as well. Already, in a branch, hidden from Bjorn & Tejun eyes ;) > All a lot of bother for no real gain IMHO. Well, I do not have a strong opinion here. I leave it to the ones who have :) But few drivers have became clearer as result of this change (and messy ones are still messy). > cheers -- Regards, Alexander Gordeev agordeev@xxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
