[PATCH] vgaarb: Stub vga_set_legacy_decoding()

[Alex Williamson]

vga_set_legacy_decoding() is defined in drivers/gpu/vga/vgaarb.c,
which is only compiled with CONFIG_VGA_ARB.  A caller would
therefore get an undefined symbol if the VGA arbiter is not
enabled.

Signed-off-by: Alex Williamson <alex.williamson at redhat.com>
---

I'd like to use this function from vfio-pci to opt-out VGA devices
from arbitration if vfio-pci VGA support is disabled.  This helps to
keep DRI2 enabled on the host if additional GPUs are installed for
VMs and used without VGA support.  I can pull this change in through
my tree if someone wants to provide just an ack.  Thanks!

 include/linux/vgaarb.h |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/vgaarb.h b/include/linux/vgaarb.h
index c37bd4d..8c3b412 100644
--- a/include/linux/vgaarb.h
+++ b/include/linux/vgaarb.h
@@ -65,8 +65,13 @@ struct pci_dev;
  *     out of the arbitration process (and can be safe to take
  *     interrupts at any time.
  */
+#if defined(CONFIG_VGA_ARB)
 extern void vga_set_legacy_decoding(struct pci_dev *pdev,
 				    unsigned int decodes);
+#else
+static inline void vga_set_legacy_decoding(struct pci_dev *pdev,
+					   unsigned int decodes) { };
+#endif
 
 /**
  *     vga_get         - acquire & locks VGA resources