drm/i915: Recognise non-VGA display devices

Starting with SandyBridge (though possible with earlier hacked BIOSes),
the BIOS may initialise the IGFX as secondary to a discrete GPU. Prior,
it would simply disable the integrated GPU. So we adjust our PCI class
mask to match any DISPLAY_CLASS device.

In such a configuration, the IGFX is not a primary VGA controller and
so should not take part in VGA arbitration, and the error return from
vga_client_register() is expected.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org

3 files changed, 10 insertions, 4 deletions

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 665898124200..17bd766f2081 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1215,9 +1215,15 @@ static int i915_load_modeset_init(struct drm_device *dev)
         if (ret)
                 DRM_INFO("failed to find VBIOS tables\n");
 
-        /* if we have > 1 VGA cards, then disable the radeon VGA resources */
+        /* If we have > 1 VGA cards, then we need to arbitrate access
+         * to the common VGA resources.
+         *
+         * If we are a secondary display controller (!PCI_DISPLAY_CLASS_VGA),
+         * then we do not take part in VGA arbitration and the
+         * vga_client_register() fails with -ENODEV.
+         */
         ret = vga_client_register(dev->pdev, dev, NULL, i915_vga_set_decode);
-        if (ret)
+        if (ret && ret != -ENODEV)
                 goto cleanup_ringbuffer;
 
         intel_register_dsm_handler();
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 72fea2bcfc4f..59eb19b13b3f 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -60,7 +60,7 @@ extern int intel_agp_enabled;
 
 #define INTEL_VGA_DEVICE(id, info) {            \
         .class = PCI_CLASS_DISPLAY_VGA << 8,    \
-        .class_mask = 0xffff00,                 \
+        .class_mask = 0xff0000,                 \
         .vendor = 0x8086,                       \
         .device = id,                           \
         .subvendor = PCI_ANY_ID,                \
diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index c380c65da417..ace2b1623b21 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/vgaarb.c
@@ -636,7 +636,7 @@ int vga_client_register(struct pci_dev *pdev, void *cookie,
                         void (*irq_set_state)(void *cookie, bool state),
                         unsigned int (*set_vga_decode)(void *cookie, bool decode))
 {
-        int ret = -1;
+        int ret = -ENODEV;
         struct vga_device *vgadev;
         unsigned long flags;