vgaarb: Add support for setting the default video device (v2)

The default VGA device is a somewhat fluid concept on platforms with
multiple GPUs. Add support for setting it so switching code can update
things appropriately, and make sure that the sysfs code returns the right
device if it's changed.

v2: Updated to fix builds when __ARCH_HAS_VGA_DEFAULT_DEVICE is false.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Acked-by: benh@kernel.crashing.org
Cc: airlied@redhat.com
Signed-off-by: Dave Airlie <airlied@redhat.com>

3 files changed, 14 insertions, 0 deletions

diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index 111d956d8e7d..e223b96fa6a0 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/vgaarb.c
@@ -136,6 +136,11 @@ struct pci_dev *vga_default_device(void)
 {
         return vga_default;
 }
+
+void vga_set_default_device(struct pci_dev *pdev)
+{
+        vga_default = pdev;
+}
 #endif
 
 static inline void vga_irq_set_state(struct vga_device *vgadev, bool state)
@@ -605,10 +610,12 @@ static bool vga_arbiter_del_pci_device(struct pci_dev *pdev)
                 goto bail;
         }
 
+#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
         if (vga_default == pdev) {
                 pci_dev_put(vga_default);
                 vga_default = NULL;
         }
+#endif
 
         if (vgadev->decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
                 vga_decode_count--;
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index a55e248618cd..86c63fe45d11 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -27,6 +27,7 @@
 #include <linux/security.h>
 #include <linux/pci-aspm.h>
 #include <linux/slab.h>
+#include <linux/vgaarb.h>
 #include "pci.h"
 
 static int sysfs_initialized;   /* = 0 */
@@ -417,6 +418,10 @@ static ssize_t
 boot_vga_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
         struct pci_dev *pdev = to_pci_dev(dev);
+        struct pci_dev *vga_dev = vga_default_device();
+
+        if (vga_dev)
+                return sprintf(buf, "%u\n", (pdev == vga_dev));
 
         return sprintf(buf, "%u\n",
                 !!(pdev->resource[PCI_ROM_RESOURCE].flags &
diff --git a/include/linux/vgaarb.h b/include/linux/vgaarb.h
index 9c3120dca294..759a25ba0539 100644
--- a/include/linux/vgaarb.h
+++ b/include/linux/vgaarb.h
@@ -31,6 +31,7 @@
 #ifndef LINUX_VGA_H
 #define LINUX_VGA_H
 
+#include <video/vga.h>
 
 /* Legacy VGA regions */
 #define VGA_RSRC_NONE          0x00
@@ -181,6 +182,7 @@ extern void vga_put(struct pci_dev *pdev, unsigned int rsrc);
 
 #ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
 extern struct pci_dev *vga_default_device(void);
+extern void vga_set_default_device(struct pci_dev *pdev);
 #endif
 
 /**