2 files changed, 34 insertions, 7 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_irq_kms.c b/drivers/gpu/drm/radeon/radeon_irq_kms.c
index 3cfd60fd0083..ea4c645ece11 100644
--- a/drivers/gpu/drm/radeon/radeon_irq_kms.c
+++ b/drivers/gpu/drm/radeon/radeon_irq_kms.c
@@ -116,13 +116,7 @@ int radeon_irq_kms_init(struct radeon_device *rdev)
         }
         /* enable msi */
         rdev->msi_enabled = 0;
-        /* MSIs don't seem to work on my rs780;
-         * not sure about rs880 or other rs780s.
-         * Needs more investigation.
-         */
-        if ((rdev->family >= CHIP_RV380) &&
-            (rdev->family != CHIP_RS780) &&
-            (rdev->family != CHIP_RS880)) {
+        if (rdev->family >= CHIP_RV380) {
                 int ret = pci_enable_msi(rdev->pdev);
                 if (!ret) {
                         rdev->msi_enabled = 1;
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 8284958fc530..bb5b46abc996 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -2493,6 +2493,39 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x4374,
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x4375,
                         quirk_msi_intx_disable_bug);
 
+/*
+ * MSI does not work with the AMD RS780/RS880 internal graphics and HDMI audio
+ * devices unless the BIOS has initialized the nb_cntl.strap_msi_enable bit.
+ */
+static void __init rs780_int_gfx_disable_msi(struct pci_dev *int_gfx_bridge)
+{
+        u32 nb_cntl;
+
+        if (!int_gfx_bridge->subordinate)
+                return;
+
+        pci_bus_write_config_dword(int_gfx_bridge->bus, PCI_DEVFN(0, 0),
+                                   0x60, 0);
+        pci_bus_read_config_dword(int_gfx_bridge->bus, PCI_DEVFN(0, 0),
+                                  0x64, &nb_cntl);
+
+        if (!(nb_cntl & BIT(10))) {
+                dev_warn(&int_gfx_bridge->dev,
+                         FW_WARN "RS780: MSI for internal graphics disabled\n");
+                int_gfx_bridge->subordinate->bus_flags |= PCI_BUS_FLAGS_NO_MSI;
+        }
+}
+
+#define PCI_DEVICE_ID_AMD_RS780_P2P_INT_GFX     0x9602
+
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AMD,
+                        PCI_DEVICE_ID_AMD_RS780_P2P_INT_GFX,
+                        rs780_int_gfx_disable_msi);
+/* wrong vendor ID on M4A785TD motherboard: */
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ASUSTEK,
+                        PCI_DEVICE_ID_AMD_RS780_P2P_INT_GFX,
+                        rs780_int_gfx_disable_msi);
+
 #endif /* CONFIG_PCI_MSI */
 
 #ifdef CONFIG_PCI_IOV