[PATCH] drm/amdgpu: Prefer default discovery offset

If a valid signature is seen at the default offset, use the default
size/offset for discovery.

Fixes: 01bdc7e219c4 ("drm/amdgpu: New interface to get IP discovery binary v3")
Closes: https://gitlab.freedesktop.org/drm/amd/-/work_items/5447

Signed-off-by: Lijo Lazar <[email protected]>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
index 44e7d2e3e6df..186661c94d8c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
@@ -334,6 +334,19 @@ static int amdgpu_discovery_get_tmr_info(struct amdgpu_device *adev,
 			goto out;
 		}
 	} else {
+		if (adev->discovery.offset) {
+			u32 signature;
+
+			/* If VRAM holds a valid discovery signature at the default
+			 * discovery offset, use it as-is.
+			 */
+			amdgpu_device_vram_access(adev, adev->discovery.offset,
+						  &signature, sizeof(signature),
+						  false);
+			if (le32_to_cpu(signature) == BINARY_SIGNATURE)
+				goto out;
+		}
+
 		tmr_size = RREG32(mmDRIVER_SCRATCH_2);
 		if (tmr_size) {
 			/* It's preferred to transition to PSP mailbox reg interface
-- 
2.49.0