[PATCH 7.1 114/228] drm/amdgpu: Prefer default discovery offset

7.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lijo Lazar <[email protected]>

commit ac828b94e027d29af82325fcc55556dc8173fd85 upstream.

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]>
Reviewed-by: Alex Deucher <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
(cherry picked from commit 46a0df99a0b2fa2fa61d864b04b6a5d5fe748779)
Cc: [email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c |   13 +++++++++++++
 1 file changed, 13 insertions(+)

--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c
@@ -310,6 +310,19 @@ static int amdgpu_discovery_get_tmr_info
 			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