drm/amdgpu: require a root bus window above 4GB for BAR resize

Don't even try to resize the BAR when there is no window above 4GB.

Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 636a913..4e668b7 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -764,6 +764,9 @@ int amdgpu_device_resize_fb_bar(struct amdgpu_device *adev)
 {
        u64 space_needed = roundup_pow_of_two(adev->mc.real_vram_size);
        u32 rbar_size = order_base_2(((space_needed >> 20) | 1)) - 1;
+       struct pci_bus *root;
+       struct resource *res;
+       unsigned i;
        u16 cmd;
        int r;
 
@@ -771,6 +774,21 @@ int amdgpu_device_resize_fb_bar(struct amdgpu_device *adev)
        if (amdgpu_sriov_vf(adev))
                return 0;
 
+       /* Check if the root BUS has 64bit memory resources */
+       root = adev->pdev->bus;
+       while (root->parent)
+               root = root->parent;
+
+       pci_bus_for_each_resource(root, res, i) {
+               if (res && res->flags & IORESOURCE_MEM_64 &&
+                   res->start > 0x100000000ull)
+                       break;
+       }
+
+       /* Trying to resize is pointless without a root hub window above 4GB */
+       if (!res)
+               return 0;
+
        /* Disable memory decoding while we change the BAR addresses and size */
        pci_read_config_word(adev->pdev, PCI_COMMAND, &cmd);
        pci_write_config_word(adev->pdev, PCI_COMMAND,