drm/vgaarb: add VGA arbitration support to the drm and kms.

VGA arb requires DRM support for non-kms drivers, to turn on/off
irqs when disabling the mem/io regions.

VGA arb requires KMS support for GPUs where we can turn off VGA
decoding. Currently we know how to do this for intel and radeon
kms drivers, which allows them to be removed from the arbiter.

This patch comes from Fedora rawhide kernel.

Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 9909505d070a..5a49a1867b35 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -33,6 +33,7 @@
 #include "intel_drv.h"
 #include "i915_drm.h"
 #include "i915_drv.h"
+#include <linux/vgaarb.h>
 
 /* Really want an OS-independent resettable timer.  Would like to have
  * this loop run for (eg) 3 sec, but have the timer reset every time
@@ -1012,6 +1013,19 @@ static int i915_probe_agp(struct drm_device *dev, uint32_t *aperture_size,
         return 0;
 }
 
+/* true = enable decode, false = disable decoder */
+static unsigned int i915_vga_set_decode(void *cookie, bool state)
+{
+        struct drm_device *dev = cookie;
+
+        intel_modeset_vga_set_state(dev, state);
+        if (state)
+                return VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
+                       VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
+        else
+                return VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
+}
+
 static int i915_load_modeset_init(struct drm_device *dev,
                                   unsigned long prealloc_size,
                                   unsigned long agp_size)
@@ -1057,6 +1071,11 @@ 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 */
+        ret = vga_client_register(dev->pdev, dev, NULL, i915_vga_set_decode);
+        if (ret)
+                goto destroy_ringbuffer;
+
         ret = drm_irq_install(dev);
         if (ret)
                 goto destroy_ringbuffer;
@@ -1324,6 +1343,7 @@ int i915_driver_unload(struct drm_device *dev)
 
         if (drm_core_check_feature(dev, DRIVER_MODESET)) {
                 drm_irq_uninstall(dev);
+                vga_client_register(dev->pdev, NULL, NULL, NULL);
         }
 
         if (dev->pdev->msi_enabled)