drm/amdgpu: add check before enabling/disabling broadcast mode

[ Upstream commit 6e807535 ]

When security violation from new vbios happens, data fabric is
risky to stop working. So prevent the direct access to DF
mmFabricConfigAccessControl from the new vbios and onwards.
Signed-off-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/gpu/drm/amd/amdgpu/df_v3_6.c

@@ -75,23 +75,29 @@ static void df_v3_6_update_medium_grain_clock_gating(struct amdgpu_device *adev,
 {
 	u32 tmp;
 
-	/* Put DF on broadcast mode */
-	adev->df_funcs->enable_broadcast_mode(adev, true);
-
-	if (enable && (adev->cg_flags & AMD_CG_SUPPORT_DF_MGCG)) {
-		tmp = RREG32_SOC15(DF, 0, mmDF_PIE_AON0_DfGlobalClkGater);
-		tmp &= ~DF_PIE_AON0_DfGlobalClkGater__MGCGMode_MASK;
-		tmp |= DF_V3_6_MGCG_ENABLE_15_CYCLE_DELAY;
-		WREG32_SOC15(DF, 0, mmDF_PIE_AON0_DfGlobalClkGater, tmp);
-	} else {
-		tmp = RREG32_SOC15(DF, 0, mmDF_PIE_AON0_DfGlobalClkGater);
-		tmp &= ~DF_PIE_AON0_DfGlobalClkGater__MGCGMode_MASK;
-		tmp |= DF_V3_6_MGCG_DISABLE;
-		WREG32_SOC15(DF, 0, mmDF_PIE_AON0_DfGlobalClkGater, tmp);
+	if (adev->cg_flags & AMD_CG_SUPPORT_DF_MGCG) {
+		/* Put DF on broadcast mode */
+		adev->df_funcs->enable_broadcast_mode(adev, true);
+
+		if (enable) {
+			tmp = RREG32_SOC15(DF, 0,
+					mmDF_PIE_AON0_DfGlobalClkGater);
+			tmp &= ~DF_PIE_AON0_DfGlobalClkGater__MGCGMode_MASK;
+			tmp |= DF_V3_6_MGCG_ENABLE_15_CYCLE_DELAY;
+			WREG32_SOC15(DF, 0,
+					mmDF_PIE_AON0_DfGlobalClkGater, tmp);
+		} else {
+			tmp = RREG32_SOC15(DF, 0,
+					mmDF_PIE_AON0_DfGlobalClkGater);
+			tmp &= ~DF_PIE_AON0_DfGlobalClkGater__MGCGMode_MASK;
+			tmp |= DF_V3_6_MGCG_DISABLE;
+			WREG32_SOC15(DF, 0,
+					mmDF_PIE_AON0_DfGlobalClkGater, tmp);
+		}
+
+		/* Exit broadcast mode */
+		adev->df_funcs->enable_broadcast_mode(adev, false);
 	}
-
-	/* Exit broadcast mode */
-	adev->df_funcs->enable_broadcast_mode(adev, false);
 }
 
 static void df_v3_6_get_clockgating_state(struct amdgpu_device *adev,