diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index e6b371e986ee..47baf2fe8f71 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7399,9 +7399,10 @@ enum {
 #define  BDW_DPRS_MASK_VBLANK_SRD	(1 << 0)
 #define CHICKEN_PIPESL_1(pipe) _MMIO_PIPE(pipe, _CHICKEN_PIPESL_1_A, _CHICKEN_PIPESL_1_B)
 
-#define CHICKEN_TRANS_A         0x420c0
-#define CHICKEN_TRANS_B         0x420c4
-#define CHICKEN_TRANS(trans) _MMIO_TRANS(trans, CHICKEN_TRANS_A, CHICKEN_TRANS_B)
+#define CHICKEN_TRANS_A		_MMIO(0x420c0)
+#define CHICKEN_TRANS_B		_MMIO(0x420c4)
+#define CHICKEN_TRANS_C		_MMIO(0x420c8)
+#define CHICKEN_TRANS_EDP	_MMIO(0x420cc)
 #define  VSC_DATA_SEL_SOFTWARE_CONTROL	(1 << 25) /* GLK and CNL+ */
 #define  DDI_TRAINING_OVERRIDE_ENABLE	(1 << 19)
 #define  DDI_TRAINING_OVERRIDE_VALUE	(1 << 18)
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 040483c96029..ad11540ac436 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -3380,6 +3380,26 @@ static void intel_enable_ddi_dp(struct intel_encoder *encoder,
 		intel_audio_codec_enable(encoder, crtc_state, conn_state);
 }
 
+static i915_reg_t
+gen9_chicken_trans_reg_by_port(struct drm_i915_private *dev_priv,
+			       enum port port)
+{
+	static const i915_reg_t regs[] = {
+		[PORT_A] = CHICKEN_TRANS_EDP,
+		[PORT_B] = CHICKEN_TRANS_A,
+		[PORT_C] = CHICKEN_TRANS_B,
+		[PORT_D] = CHICKEN_TRANS_C,
+		[PORT_E] = CHICKEN_TRANS_A,
+	};
+
+	WARN_ON(INTEL_GEN(dev_priv) < 9);
+
+	if (WARN_ON(port < PORT_A || port > PORT_E))
+		port = PORT_A;
+
+	return regs[port];
+}
+
 static void intel_enable_ddi_hdmi(struct intel_encoder *encoder,
 				  const struct intel_crtc_state *crtc_state,
 				  const struct drm_connector_state *conn_state)
@@ -3403,17 +3423,10 @@ static void intel_enable_ddi_hdmi(struct intel_encoder *encoder,
 		 * the bits affect a specific DDI port rather than
 		 * a specific transcoder.
 		 */
-		static const enum transcoder port_to_transcoder[] = {
-			[PORT_A] = TRANSCODER_EDP,
-			[PORT_B] = TRANSCODER_A,
-			[PORT_C] = TRANSCODER_B,
-			[PORT_D] = TRANSCODER_C,
-			[PORT_E] = TRANSCODER_A,
-		};
-		enum transcoder transcoder = port_to_transcoder[port];
+		i915_reg_t reg = gen9_chicken_trans_reg_by_port(dev_priv, port);
 		u32 val;
 
-		val = I915_READ(CHICKEN_TRANS(transcoder));
+		val = I915_READ(reg);
 
 		if (port == PORT_E)
 			val |= DDIE_TRAINING_OVERRIDE_ENABLE |
@@ -3422,8 +3435,8 @@ static void intel_enable_ddi_hdmi(struct intel_encoder *encoder,
 			val |= DDI_TRAINING_OVERRIDE_ENABLE |
 				DDI_TRAINING_OVERRIDE_VALUE;
 
-		I915_WRITE(CHICKEN_TRANS(transcoder), val);
-		POSTING_READ(CHICKEN_TRANS(transcoder));
+		I915_WRITE(reg, val);
+		POSTING_READ(reg);
 
 		udelay(1);
 
@@ -3434,7 +3447,7 @@ static void intel_enable_ddi_hdmi(struct intel_encoder *encoder,
 			val &= ~(DDI_TRAINING_OVERRIDE_ENABLE |
 				 DDI_TRAINING_OVERRIDE_VALUE);
 
-		I915_WRITE(CHICKEN_TRANS(transcoder), val);
+		I915_WRITE(reg, val);
 	}
 
 	/* In HDMI/DVI mode, the port width, and swing/emphasis values
diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
index 26292961d693..54fa17a5596a 100644
--- a/drivers/gpu/drm/i915/intel_psr.c
+++ b/drivers/gpu/drm/i915/intel_psr.c
@@ -577,6 +577,25 @@ static void intel_psr_activate(struct intel_dp *intel_dp)
 	dev_priv->psr.active = true;
 }
 
+static i915_reg_t gen9_chicken_trans_reg(struct drm_i915_private *dev_priv,
+					 enum transcoder cpu_transcoder)
+{
+	static const i915_reg_t regs[] = {
+		[TRANSCODER_A] = CHICKEN_TRANS_A,
+		[TRANSCODER_B] = CHICKEN_TRANS_B,
+		[TRANSCODER_C] = CHICKEN_TRANS_C,
+		[TRANSCODER_EDP] = CHICKEN_TRANS_EDP,
+	};
+
+	WARN_ON(INTEL_GEN(dev_priv) < 9);
+
+	if (WARN_ON(cpu_transcoder >= ARRAY_SIZE(regs) ||
+		    !regs[cpu_transcoder].reg))
+		cpu_transcoder = TRANSCODER_A;
+
+	return regs[cpu_transcoder];
+}
+
 static void intel_psr_enable_source(struct intel_dp *intel_dp,
 				    const struct intel_crtc_state *crtc_state)
 {
@@ -591,7 +610,9 @@ static void intel_psr_enable_source(struct intel_dp *intel_dp,
 		hsw_psr_setup_aux(intel_dp);
 
 	if (dev_priv->psr.psr2_enabled) {
-		u32 chicken = I915_READ(CHICKEN_TRANS(cpu_transcoder));
+		i915_reg_t reg = gen9_chicken_trans_reg(dev_priv,
+							cpu_transcoder);
+		u32 chicken = I915_READ(reg);
 
 		if (IS_GEN9(dev_priv) && !IS_GEMINILAKE(dev_priv))
 			chicken |= (PSR2_VSC_ENABLE_PROG_HEADER
@@ -599,7 +620,7 @@ static void intel_psr_enable_source(struct intel_dp *intel_dp,
 
 		else
 			chicken &= ~VSC_DATA_SEL_SOFTWARE_CONTROL;
-		I915_WRITE(CHICKEN_TRANS(cpu_transcoder), chicken);
+		I915_WRITE(reg, chicken);
 	}
 
 	/*