[PATCH] drm/amdgpu: Prefer default discovery offset

[Lijo Lazar]

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 <lijo.la...@amd.com>
---
 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