#define DP0_STARTVAL           0x064c
 #define DP0_ACTIVEVAL          0x0650
 #define DP0_SYNCVAL            0x0654
+#define SYNCVAL_HS_POL_ACTIVE_LOW      (1 << 15)
+#define SYNCVAL_VS_POL_ACTIVE_LOW      (1 << 31)
 #define DP0_MISC               0x0658
 #define TU_SIZE_RECOMMENDED            (63) /* LSCLK cycles per TU */
 #define BPC_6                          (0 << 5)
 
        tc_write(DP0_ACTIVEVAL, (mode->vdisplay << 16) | (mode->hdisplay));
 
-       tc_write(DP0_SYNCVAL, (vsync_len << 16) | (hsync_len << 0));
+       tc_write(DP0_SYNCVAL, (vsync_len << 16) | (hsync_len << 0) |
+                ((mode->flags & DRM_MODE_FLAG_NHSYNC) ? SYNCVAL_HS_POL_ACTIVE_LOW : 0) |
+                ((mode->flags & DRM_MODE_FLAG_NVSYNC) ? SYNCVAL_VS_POL_ACTIVE_LOW : 0));
 
        tc_write(DPIPXLFMT, VS_POL_ACTIVE_LOW | HS_POL_ACTIVE_LOW |
                 DE_POL_ACTIVE_HIGH | SUB_CFG_TYPE_CONFIG1 | DPI_BPP_RGB888);