drm/ttm/radeon: add dma32 support.

This add support for using dma32 memory on gpus that really need it.

Currently IGPs are left without DMA32 but we might need to change
that unless we can fix rs690.

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

1 files changed, 15 insertions, 2 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index 332911267eb..27a5ac96995 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -450,6 +450,7 @@ int radeon_device_init(struct radeon_device *rdev,
                        uint32_t flags)
 {
         int r, ret;
+        int dma_bits;
 
         DRM_INFO("radeon: Initializing kernel modesetting.\n");
         rdev->shutdown = false;
@@ -492,8 +493,20 @@ int radeon_device_init(struct radeon_device *rdev,
                 return r;
         }
 
-        /* Report DMA addressing limitation */
-        r = pci_set_dma_mask(rdev->pdev, DMA_BIT_MASK(32));
+        /* set DMA mask + need_dma32 flags.
+         * PCIE - can handle 40-bits.
+         * IGP - can handle 40-bits (in theory)
+         * AGP - generally dma32 is safest
+         * PCI - only dma32
+         */
+        rdev->need_dma32 = false;
+        if (rdev->flags & RADEON_IS_AGP)
+                rdev->need_dma32 = true;
+        if (rdev->flags & RADEON_IS_PCI)
+                rdev->need_dma32 = true;
+
+        dma_bits = rdev->need_dma32 ? 32 : 40;
+        r = pci_set_dma_mask(rdev->pdev, DMA_BIT_MASK(dma_bits));
         if (r) {
                 printk(KERN_WARNING "radeon: No suitable DMA available.\n");
         }