[PATCH] PCI: Add a comment for the is_physfn field

[Oliver O'Halloran <oohall@gmail.com>]

The meaning of is_physfn and how it's different to is_virtfn really
isn't clear unless you do a bit of digging. Add a comment to help out
the unaware.

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
---
 include/linux/pci.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 77448215ef5b..88bf71bfa757 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -393,6 +393,10 @@ struct pci_dev {
 	unsigned int	is_managed:1;
 	unsigned int	needs_freset:1;		/* Requires fundamental reset */
 	unsigned int	state_saved:1;
+	/*
+	 * is_physfn indicates that the function can be used to host VFs.
+	 * It is only set when both the kernel and the device support IOV.
+	 */
 	unsigned int	is_physfn:1;
 	unsigned int	is_virtfn:1;
 	unsigned int	reset_fn:1;
-- 
2.20.1