3 files changed, 15 insertions, 1 deletions

diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
index ae4c857fb17..8ff7cac222d 100644
--- a/drivers/gpu/drm/radeon/r100.c
+++ b/drivers/gpu/drm/radeon/r100.c
@@ -4141,8 +4141,15 @@ uint32_t r100_mm_rreg(struct radeon_device *rdev, uint32_t reg,
         if (reg < rdev->rmmio_size && !always_indirect)
                 return readl(((void __iomem *)rdev->rmmio) + reg);
         else {
+                unsigned long flags;
+                uint32_t ret;
+
+                spin_lock_irqsave(&rdev->mmio_idx_lock, flags);
                 writel(reg, ((void __iomem *)rdev->rmmio) + RADEON_MM_INDEX);
-                return readl(((void __iomem *)rdev->rmmio) + RADEON_MM_DATA);
+                ret = readl(((void __iomem *)rdev->rmmio) + RADEON_MM_DATA);
+                spin_unlock_irqrestore(&rdev->mmio_idx_lock, flags);
+
+                return ret;
         }
 }
 
@@ -4152,8 +4159,12 @@ void r100_mm_wreg(struct radeon_device *rdev, uint32_t reg, uint32_t v,
         if (reg < rdev->rmmio_size && !always_indirect)
                 writel(v, ((void __iomem *)rdev->rmmio) + reg);
         else {
+                unsigned long flags;
+
+                spin_lock_irqsave(&rdev->mmio_idx_lock, flags);
                 writel(reg, ((void __iomem *)rdev->rmmio) + RADEON_MM_INDEX);
                 writel(v, ((void __iomem *)rdev->rmmio) + RADEON_MM_DATA);
+                spin_unlock_irqrestore(&rdev->mmio_idx_lock, flags);
         }
 }
 
diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index 609bb18d09f..285fb3f203a 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -1556,6 +1556,8 @@ struct radeon_device {
         /* Register mmio */
         resource_size_t                 rmmio_base;
         resource_size_t                 rmmio_size;
+        /* protects concurrent MM_INDEX/DATA based register access */
+        spinlock_t mmio_idx_lock;
         void __iomem                    *rmmio;
         radeon_rreg_t                   mc_rreg;
         radeon_wreg_t                   mc_wreg;
diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index e2f5f888c37..49b06590001 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -1059,6 +1059,7 @@ int radeon_device_init(struct radeon_device *rdev,
 
         /* Registers mapping */
         /* TODO: block userspace mapping of io register */
+        spin_lock_init(&rdev->mmio_idx_lock);
         rdev->rmmio_base = pci_resource_start(rdev->pdev, 2);
         rdev->rmmio_size = pci_resource_len(rdev->pdev, 2);
         rdev->rmmio = ioremap(rdev->rmmio_base, rdev->rmmio_size);