diff --git a/drivers/gpu/drm/sun4i/sun4i_frontend.c b/drivers/gpu/drm/sun4i/sun4i_frontend.c
index 7462801b1fa8..c4959d9e1639 100644
--- a/drivers/gpu/drm/sun4i/sun4i_frontend.c
+++ b/drivers/gpu/drm/sun4i/sun4i_frontend.c
@@ -407,6 +407,7 @@ int sun4i_frontend_update_formats(struct sun4i_frontend *frontend,
 	struct drm_framebuffer *fb = state->fb;
 	const struct drm_format_info *format = fb->format;
 	uint64_t modifier = fb->modifier;
+	unsigned int ch1_phase_idx;
 	u32 out_fmt_val;
 	u32 in_fmt_val, in_mod_val, in_ps_val;
 	unsigned int i;
@@ -442,18 +443,19 @@ int sun4i_frontend_update_formats(struct sun4i_frontend *frontend,
 	 * I have no idea what this does exactly, but it seems to be
 	 * related to the scaler FIR filter phase parameters.
 	 */
+	ch1_phase_idx = (format->num_planes > 1) ? 1 : 0;
 	regmap_write(frontend->regs, SUN4I_FRONTEND_CH0_HORZPHASE_REG,
 		     frontend->data->ch_phase[0]);
 	regmap_write(frontend->regs, SUN4I_FRONTEND_CH1_HORZPHASE_REG,
-		     frontend->data->ch_phase[1]);
+		     frontend->data->ch_phase[ch1_phase_idx]);
 	regmap_write(frontend->regs, SUN4I_FRONTEND_CH0_VERTPHASE0_REG,
 		     frontend->data->ch_phase[0]);
 	regmap_write(frontend->regs, SUN4I_FRONTEND_CH1_VERTPHASE0_REG,
-		     frontend->data->ch_phase[1]);
+		     frontend->data->ch_phase[ch1_phase_idx]);
 	regmap_write(frontend->regs, SUN4I_FRONTEND_CH0_VERTPHASE1_REG,
 		     frontend->data->ch_phase[0]);
 	regmap_write(frontend->regs, SUN4I_FRONTEND_CH1_VERTPHASE1_REG,
-		     frontend->data->ch_phase[1]);
+		     frontend->data->ch_phase[ch1_phase_idx]);
 
 	/*
 	 * Checking the input format is sufficient since we currently only