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>

5 files changed, 40 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)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 77ed060b4292..a0632f8e76ac 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -766,6 +766,7 @@ static inline void opregion_enable_asle(struct drm_device *dev) { return; }
 /* modesetting */
 extern void intel_modeset_init(struct drm_device *dev);
 extern void intel_modeset_cleanup(struct drm_device *dev);
+extern int intel_modeset_vga_set_state(struct drm_device *dev, bool state);
 
 /**
  * Lock test for when it's just for synchronization of ring access.
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index e38cd21161c8..3f7963553464 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -30,6 +30,7 @@
  * fb aperture size and the amount of pre-reserved memory.
  */
 #define INTEL_GMCH_CTRL         0x52
+#define INTEL_GMCH_VGA_DISABLE  (1 << 1)
 #define INTEL_GMCH_ENABLED      0x4
 #define INTEL_GMCH_MEM_MASK     0x1
 #define INTEL_GMCH_MEM_64M      0x1
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 155719ff99d1..0227b1652906 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3917,3 +3917,20 @@ struct drm_encoder *intel_best_encoder(struct drm_connector *connector)
 
         return &intel_output->enc;
 }
+
+/*
+ * set vga decode state - true == enable VGA decode
+ */
+int intel_modeset_vga_set_state(struct drm_device *dev, bool state)
+{
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        u16 gmch_ctrl;
+
+        pci_read_config_word(dev_priv->bridge_dev, INTEL_GMCH_CTRL, &gmch_ctrl);
+        if (state)
+                gmch_ctrl &= ~INTEL_GMCH_VGA_DISABLE;
+        else
+                gmch_ctrl |= INTEL_GMCH_VGA_DISABLE;
+        pci_write_config_word(dev_priv->bridge_dev, INTEL_GMCH_CTRL, gmch_ctrl);
+        return 0;
+}
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index b9e47f1e1cc0..3a0004f755d0 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -178,4 +178,5 @@ extern int intel_framebuffer_create(struct drm_device *dev,
                                     struct drm_mode_fb_cmd *mode_cmd,
                                     struct drm_framebuffer **fb,
                                     struct drm_gem_object *obj);
+
 #endif /* __INTEL_DRV_H__ */