diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index d6f9d5f3b15b..4834c90b4912 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
@@ -12,6 +12,7 @@
 
 #include <drm/drmP.h>
 #include <drm/drm_atomic_helper.h>
+#include <drm/drm_connector.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_encoder.h>
@@ -277,6 +278,57 @@ static void sun4i_tcon0_mode_set_common(struct sun4i_tcon *tcon,
 		     SUN4I_TCON0_BASIC0_Y(mode->crtc_vdisplay));
 }
 
+static void sun4i_tcon0_mode_set_dithering(struct sun4i_tcon *tcon,
+					   const struct drm_connector *connector)
+{
+	u32 bus_format = 0;
+	u32 val = 0;
+
+	/* XXX Would this ever happen? */
+	if (!connector)
+		return;
+
+	/*
+	 * FIXME: Undocumented bits
+	 *
+	 * The whole dithering process and these parameters are not
+	 * explained in the vendor documents or BSP kernel code.
+	 */
+	regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED_PR_REG, 0x11111111);
+	regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED_PG_REG, 0x11111111);
+	regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED_PB_REG, 0x11111111);
+	regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED_LR_REG, 0x11111111);
+	regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED_LG_REG, 0x11111111);
+	regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED_LB_REG, 0x11111111);
+	regmap_write(tcon->regs, SUN4I_TCON0_FRM_TBL0_REG, 0x01010000);
+	regmap_write(tcon->regs, SUN4I_TCON0_FRM_TBL1_REG, 0x15151111);
+	regmap_write(tcon->regs, SUN4I_TCON0_FRM_TBL2_REG, 0x57575555);
+	regmap_write(tcon->regs, SUN4I_TCON0_FRM_TBL3_REG, 0x7f7f7777);
+
+	/* Do dithering if panel only supports 6 bits per color */
+	if (connector->display_info.bpc == 6)
+		val |= SUN4I_TCON0_FRM_CTL_EN;
+
+	if (connector->display_info.num_bus_formats == 1)
+		bus_format = connector->display_info.bus_formats[0];
+
+	/* Check the connection format */
+	switch (bus_format) {
+	case MEDIA_BUS_FMT_RGB565_1X16:
+		/* R and B components are only 5 bits deep */
+		val |= SUN4I_TCON0_FRM_CTL_MODE_R;
+		val |= SUN4I_TCON0_FRM_CTL_MODE_B;
+	case MEDIA_BUS_FMT_RGB666_1X18:
+	case MEDIA_BUS_FMT_RGB666_1X7X3_SPWG:
+		/* Fall through: enable dithering */
+		val |= SUN4I_TCON0_FRM_CTL_EN;
+		break;
+	}
+
+	/* Write dithering settings */
+	regmap_write(tcon->regs, SUN4I_TCON_FRM_CTL_REG, val);
+}
+
 static void sun4i_tcon0_mode_set_cpu(struct sun4i_tcon *tcon,
 				     const struct drm_encoder *encoder,
 				     const struct drm_display_mode *mode)
@@ -294,6 +346,9 @@ static void sun4i_tcon0_mode_set_cpu(struct sun4i_tcon *tcon,
 
 	sun4i_tcon0_mode_set_common(tcon, mode);
 
+	/* Set dithering if needed */
+	sun4i_tcon0_mode_set_dithering(tcon, sun4i_tcon_get_connector(encoder));
+
 	regmap_update_bits(tcon->regs, SUN4I_TCON0_CTL_REG,
 			   SUN4I_TCON0_CTL_IF_MASK,
 			   SUN4I_TCON0_CTL_IF_8080);
@@ -359,6 +414,9 @@ static void sun4i_tcon0_mode_set_lvds(struct sun4i_tcon *tcon,
 	tcon->dclk_max_div = 7;
 	sun4i_tcon0_mode_set_common(tcon, mode);
 
+	/* Set dithering if needed */
+	sun4i_tcon0_mode_set_dithering(tcon, sun4i_tcon_get_connector(encoder));
+
 	/* Adjust clock delay */
 	clk_delay = sun4i_tcon_get_clk_delay(mode, 0);
 	regmap_update_bits(tcon->regs, SUN4I_TCON0_CTL_REG,
@@ -432,6 +490,9 @@ static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon,
 	tcon->dclk_max_div = 127;
 	sun4i_tcon0_mode_set_common(tcon, mode);
 
+	/* Set dithering if needed */
+	sun4i_tcon0_mode_set_dithering(tcon, tcon->panel->connector);
+
 	/* Adjust clock delay */
 	clk_delay = sun4i_tcon_get_clk_delay(mode, 0);
 	regmap_update_bits(tcon->regs, SUN4I_TCON0_CTL_REG,