OMAPDSS: DSI: flush posted write when entering ULPS

Flush posted write between writing the ULPS enable bits and waiting for
the interrupt.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/omap2/dss/dsi.c

@@ -3561,6 +3561,9 @@ static int dsi_enter_ulps(struct platform_device *dsidev)
 	REG_FLD_MOD(dsidev, DSI_COMPLEXIO_CFG2, (1 << 0) | (1 << 1) | (1 << 2),
 		7, 5);
 
+	/* flush posted write and wait for SCP interface to finish the write */
+	dsi_read_reg(dsidev, DSI_COMPLEXIO_CFG2);
+
 	if (wait_for_completion_timeout(&completion,
 				msecs_to_jiffies(1000)) == 0) {
 		DSSERR("ULPS enable timeout\n");
@@ -3575,6 +3578,9 @@ static int dsi_enter_ulps(struct platform_device *dsidev)
 	REG_FLD_MOD(dsidev, DSI_COMPLEXIO_CFG2, (0 << 0) | (0 << 1) | (0 << 2),
 		7, 5);
 
+	/* flush posted write and wait for SCP interface to finish the write */
+	dsi_read_reg(dsidev, DSI_COMPLEXIO_CFG2);
+
 	dsi_cio_power(dsidev, DSI_COMPLEXIO_POWER_ULPS);
 
 	dsi_if_enable(dsidev, false);