drm/rockchip: dw-mipi-dsi: fix escape clock rate

Use the same calculation as the vendor kernel to derive the escape clock
speed.

Change-Id: I7aff4dc7fa9598df164148eaf44304caad704f23
Signed-off-by: xubilv <xbl@rock-chips.com>

Author: xubilv

drivers/gpu/drm/rockchip/dw-mipi-dsi.c

@@ -749,11 +749,16 @@ static void dw_mipi_dsi_set_mode(struct dw_mipi_dsi *dsi,
 
 static void dw_mipi_dsi_init(struct dw_mipi_dsi *dsi)
 {
+	u32 esc_clk_div;
+
 	dsi_write(dsi, DSI_PWR_UP, RESET);
 	dsi_write(dsi, DSI_PHY_RSTZ, PHY_DISFORCEPLL | PHY_DISABLECLK
 		  | PHY_RSTZ | PHY_SHUTDOWNZ);
+
+	/* The maximum value of the escape clock frequency is 20MHz */
+	esc_clk_div = DIV_ROUND_UP(dsi->lane_mbps >> 3, 20);
 	dsi_write(dsi, DSI_CLKMGR_CFG, TO_CLK_DIVIDSION(10) |
-		  TX_ESC_CLK_DIVIDSION(7));
+		  TX_ESC_CLK_DIVIDSION(esc_clk_div));
 }
 
 static void dw_mipi_dsi_dpi_config(struct dw_mipi_dsi *dsi,