drm/sun4i: tcon: Move out the tcon0 common setup

Some channel0 setup has to be done, no matter what the output interface is
(RGB, CPU, LVDS). Move that code into a common function in order to avoid
duplication.
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/183100/

drivers/gpu/drm/sun4i/sun4i_tcon.c

@@ -158,15 +158,26 @@ static int sun4i_tcon_get_clk_delay(const struct drm_display_mode *mode,
 	return delay;
 }
 
-static void sun4i_tcon0_mode_set(struct sun4i_tcon *tcon,
+static void sun4i_tcon0_mode_set_common(struct sun4i_tcon *tcon,
+					const struct drm_display_mode *mode)
+{
+	/* Configure the dot clock */
+	clk_set_rate(tcon->dclk, mode->crtc_clock * 1000);
+
+	/* Set the resolution */
+	regmap_write(tcon->regs, SUN4I_TCON0_BASIC0_REG,
+		     SUN4I_TCON0_BASIC0_X(mode->crtc_hdisplay) |
+		     SUN4I_TCON0_BASIC0_Y(mode->crtc_vdisplay));
+}
+
+static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon,
 				     const struct drm_display_mode *mode)
 {
 	unsigned int bp, hsync, vsync;
 	u8 clk_delay;
 	u32 val = 0;
 
-	/* Configure the dot clock */
-	clk_set_rate(tcon->dclk, mode->crtc_clock * 1000);
+	sun4i_tcon0_mode_set_common(tcon, mode);
 
 	/* Adjust clock delay */
 	clk_delay = sun4i_tcon_get_clk_delay(mode, 0);
@@ -174,11 +185,6 @@ static void sun4i_tcon0_mode_set(struct sun4i_tcon *tcon,
 			   SUN4I_TCON0_CTL_CLK_DELAY_MASK,
 			   SUN4I_TCON0_CTL_CLK_DELAY(clk_delay));
 
-	/* Set the resolution */
-	regmap_write(tcon->regs, SUN4I_TCON0_BASIC0_REG,
-		     SUN4I_TCON0_BASIC0_X(mode->crtc_hdisplay) |
-		     SUN4I_TCON0_BASIC0_Y(mode->crtc_vdisplay));
-
 	/*
 	 * This is called a backporch in the register documentation,
 	 * but it really is the back porch + hsync
@@ -329,7 +335,7 @@ void sun4i_tcon_mode_set(struct sun4i_tcon *tcon,
 {
 	switch (encoder->encoder_type) {
 	case DRM_MODE_ENCODER_NONE:
-		sun4i_tcon0_mode_set(tcon, mode);
+		sun4i_tcon0_mode_set_rgb(tcon, mode);
 		sun4i_tcon_set_mux(tcon, 0, encoder);
 		break;
 	case DRM_MODE_ENCODER_TVDAC: