drm/amdgpu: resize VRAM BAR for CPU access v6

Try to resize BAR0 to let CPU access all of VRAM.

v2: rebased, style cleanups, disable mem decode before resize,
    handle gmc_v9 as well, round size up to power of two.
v3: handle gmc_v6 as well, release and reassign all BARs in the driver.
v4: rename new function to amdgpu_device_resize_fb_bar,
    reenable mem decoding only if all resources are assigned.
v5: reorder resource release, return -ENODEV instead of BUG_ON().
v6: squash in rebase fix

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

1 files changed, 50 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 83dbd02004b0..84c8bbec27ce 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -410,6 +410,9 @@ static int amdgpu_doorbell_init(struct amdgpu_device *adev)
 		return 0;
 	}
 
+	if (pci_resource_flags(adev->pdev, 2) & IORESOURCE_UNSET)
+		return -EINVAL;
+
 	/* doorbell bar mapping */
 	adev->doorbell.base = pci_resource_start(adev->pdev, 2);
 	adev->doorbell.size = pci_resource_len(adev->pdev, 2);
@@ -749,6 +752,53 @@ error_create:
 	return r;
 }
 
+/**
+ * amdgpu_device_resize_fb_bar - try to resize FB BAR
+ *
+ * @adev: amdgpu_device pointer
+ *
+ * Try to resize FB BAR to make all VRAM CPU accessible. We try very hard not
+ * to fail, but if any of the BARs is not accessible after the size we abort
+ * driver loading by returning -ENODEV.
+ */
+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;
+	u16 cmd;
+	int r;
+
+	/* 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,
+			      cmd & ~PCI_COMMAND_MEMORY);
+
+	/* Free the VRAM and doorbell BAR, we most likely need to move both. */
+	amdgpu_doorbell_fini(adev);
+	if (adev->asic_type >= CHIP_BONAIRE)
+		pci_release_resource(adev->pdev, 2);
+
+	pci_release_resource(adev->pdev, 0);
+
+	r = pci_resize_resource(adev->pdev, 0, rbar_size);
+	if (r == -ENOSPC)
+		DRM_INFO("Not enough PCI address space for a large BAR.");
+	else if (r && r != -ENOTSUPP)
+		DRM_ERROR("Problem resizing BAR0 (%d).", r);
+
+	pci_assign_unassigned_bus_resources(adev->pdev->bus);
+
+	/* When the doorbell or fb BAR isn't available we have no chance of
+	 * using the device.
+	 */
+	r = amdgpu_doorbell_init(adev);
+	if (r || (pci_resource_flags(adev->pdev, 0) & IORESOURCE_UNSET))
+		return -ENODEV;
+
+	pci_write_config_word(adev->pdev, PCI_COMMAND, cmd);
+
+	return 0;
+}
 
 /*
  * GPU helpers function.