Subject: Re: [PATCH][BNX2]: Disable MSI on 5706 if AMD 8132 bridge is present

From: Brice Goglin <[email-masked]>
Date: Sat, 30 Sep 2006 12:13:34 +0200

Michael Chan a écrit :
> AMD believes this incompatibility is unique to the 5706, and
> prefers to locally disable MSI rather than globally disabling it
> using pci_msi_quirk.
>   

FYI, pci_msi_quirk is the extreme solution, there is something in the
middle :) It is possible to disable MSI for only devices that are behind
this bridge (by setting the NO_MSI flag in its bus flag). We just merged
a couple patchs related to this NO_MSI flag and pci_msi_quirk (there are
very very few cases where MSI must be disabled globally, most of the
time a subset behind a bridge is enough) so I am very glad that you
didn't use it :)
Anyway, disabling locally is better here.

> +	if (CHIP_NUM(bp) == CHIP_NUM_5706 && disable_msi == 0) {
> +		struct pci_dev *amd_8132 = NULL;
> +
> +		while ((amd_8132 = pci_get_device(PCI_VENDOR_ID_AMD,
> +						  PCI_DEVICE_ID_AMD_8132_BRIDGE,
> +						  amd_8132))) {
>   

What if the machine has such a bridge and board, but the board is not
actually located somewhere behind the bridge? I would rather walk the
PCI hierarchy from the board to the top and check whether we find a
AMD8132. Probably something like:

	struct pci_dev * bridge = <the bnx2 pci_dev>;
	while (bridge->bus && bridge->bus->self)
		bridge = bridge->bus->self;
		if (bridge->vendor == PCI_VENDOR_ID_AMD
		    && bridge->device == PCI_VENDOR_ID_AMD_8132_BRIDGE)
			<do your stuff to disable MSI on your board>

Brice