PCI MSI: the new interrupt routing headache

From: Jeff Garzik
Date: Thu Nov 17 2005 - 00:44:54 EST



I just got SATA working on Marvell. After fixing a bunch of issues in the driver, the final issue was lack of interrupts. Disabling CONFIG_PCI_MSI solved that, and suddenly the driver was working quite nicely.

The general problem is that pci_enable_msi() is not failing, on systems that do not support MSI. This leads to Infiniband, tg3, and other drivers working around this problem by including an MSI-interrupts-work test during probe.

Perhaps its because I like leading edge stuff, and am playing with drivers for PCI MSI hardware, but it seems like I am running into this pci_enable_msi()-doesnt-fail problem more and more frequently. First tg3, then AHCI, now sata_mv.

What needs to be done, to detect working PCI message signalled interrupts such that pci_enable_msi() fails properly?

Thanks,

Jeff



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