Re: pci_enable_msi() for everyone?

[Dave Jones <davej@redhat.com>]

On Sat, Jun 04, 2005 at 12:18:03AM -0700, Greg KH wrote:
 > On Sat, Jun 04, 2005 at 01:05:37AM -0600, Grant Grundler wrote:
 > > On Fri, Jun 03, 2005 at 11:48:21PM -0700, Greg KH wrote:
 > > > > One complication is some drivers will want to register a different
 > > > > IRQ handler depending on if MSI is enabled or not.
 > > > 
 > > > That's fine, they can always check the device capabilities and do that.
 > > 
 > > Can you be more specific?
 > > Maybe a short chunk of psuedo code?
 > 
 > Hm, here's a possible function to do it (typed into my email client, not
 > compiled, no warranties, etc...):
 > 
 > /* returns 1 if device is in MSI mode, 0 otherwise */
 > int pci_in_msi_mode(struct pci_dev *dev)
 > {
 > 	int pos;
 > 	u16 control;
 > 
 > 	pos = pci_find_capability(dev, PCI_CAP_ID_MSI);
 > 	if (!pos)
 > 		return 0;
 > 	pci_read_config_word(dev, msi_control_reg(pos), &control);
 > 	if (control & PCI_MSI_FLAGS_ENABLE);
 > 		return 1;
 > 	return 0;
 > }

What if MSI support has been disabled in the bridge due to some quirk
(like the recent AMD 8111 quirk) ?   Maybe the above function
should check pci_msi_enable as well ?

		Dave