drm/amdgpu: avoid soft lockup when waiting for RLC serdes (v2)

Normally all waiting get timeout if there's one.
Release the lock and return immediately when timeout happens.

v2:
 - set the se_sh to broadcase before return
Acked-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: Npding <Pixel.Ding@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c

@@ -3851,6 +3851,14 @@ static void gfx_v8_0_wait_for_rlc_serdes(struct amdgpu_device *adev)
 					break;
 				udelay(1);
 			}
+			if (k == adev->usec_timeout) {
+				gfx_v8_0_select_se_sh(adev, 0xffffffff,
+						      0xffffffff, 0xffffffff);
+				mutex_unlock(&adev->grbm_idx_mutex);
+				DRM_INFO("Timeout wait for RLC serdes %u,%u\n",
+					 i, j);
+				return;
+			}
 		}
 	}
 	gfx_v8_0_select_se_sh(adev, 0xffffffff, 0xffffffff, 0xffffffff);

drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c

@@ -1645,6 +1645,14 @@ static void gfx_v9_0_wait_for_rlc_serdes(struct amdgpu_device *adev)
 					break;
 				udelay(1);
 			}
+			if (k == adev->usec_timeout) {
+				gfx_v9_0_select_se_sh(adev, 0xffffffff,
+						      0xffffffff, 0xffffffff);
+				mutex_unlock(&adev->grbm_idx_mutex);
+				DRM_INFO("Timeout wait for RLC serdes %u,%u\n",
+					 i, j);
+				return;
+			}
 		}
 	}
 	gfx_v9_0_select_se_sh(adev, 0xffffffff, 0xffffffff, 0xffffffff);