diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
index 68bfe50ada59..1dbe38282ebe 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -107,7 +107,7 @@ intel_dp_aux_supports_hdr_backlight(struct intel_connector *connector)
 	u8 tcon_cap[4];
 
 	ret = drm_dp_dpcd_read(aux, INTEL_EDP_HDR_TCON_CAP0, tcon_cap, sizeof(tcon_cap));
-	if (ret < 0)
+	if (ret != sizeof(tcon_cap))
 		return false;
 
 	if (!(tcon_cap[1] & INTEL_EDP_HDR_TCON_BRIGHTNESS_NITS_CAP))
@@ -137,7 +137,7 @@ intel_dp_aux_hdr_get_backlight(struct intel_connector *connector, enum pipe pipe
 	u8 tmp;
 	u8 buf[2] = { 0 };
 
-	if (drm_dp_dpcd_readb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, &tmp) < 0) {
+	if (drm_dp_dpcd_readb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, &tmp) != 1) {
 		drm_err(&i915->drm, "Failed to read current backlight mode from DPCD\n");
 		return 0;
 	}
@@ -153,7 +153,8 @@ intel_dp_aux_hdr_get_backlight(struct intel_connector *connector, enum pipe pipe
 		return panel->backlight.max;
 	}
 
-	if (drm_dp_dpcd_read(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf, sizeof(buf)) < 0) {
+	if (drm_dp_dpcd_read(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf,
+			     sizeof(buf)) != sizeof(buf)) {
 		drm_err(&i915->drm, "Failed to read brightness from DPCD\n");
 		return 0;
 	}
@@ -172,7 +173,8 @@ intel_dp_aux_hdr_set_aux_backlight(const struct drm_connector_state *conn_state,
 	buf[0] = level & 0xFF;
 	buf[1] = (level & 0xFF00) >> 8;
 
-	if (drm_dp_dpcd_write(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf, 4) < 0)
+	if (drm_dp_dpcd_write(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf,
+			      sizeof(buf)) != sizeof(buf))
 		drm_err(dev, "Failed to write brightness level to DPCD\n");
 }
 
@@ -203,7 +205,7 @@ intel_dp_aux_hdr_enable_backlight(const struct intel_crtc_state *crtc_state,
 	u8 old_ctrl, ctrl;
 
 	ret = drm_dp_dpcd_readb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, &old_ctrl);
-	if (ret < 0) {
+	if (ret != 1) {
 		drm_err(&i915->drm, "Failed to read current backlight control mode: %d\n", ret);
 		return;
 	}
@@ -221,7 +223,7 @@ intel_dp_aux_hdr_enable_backlight(const struct intel_crtc_state *crtc_state,
 	}
 
 	if (ctrl != old_ctrl)
-		if (drm_dp_dpcd_writeb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, ctrl) < 0)
+		if (drm_dp_dpcd_writeb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, ctrl) != 1)
 			drm_err(&i915->drm, "Failed to configure DPCD brightness controls\n");
 }
 
@@ -277,8 +279,7 @@ static void set_vesa_backlight_enable(struct intel_dp *intel_dp, bool enable)
 	if (!(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP))
 		return;
 
-	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
-			      &reg_val) < 0) {
+	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER, &reg_val) != 1) {
 		drm_dbg_kms(&i915->drm, "Failed to read DPCD register 0x%x\n",
 			    DP_EDP_DISPLAY_CONTROL_REGISTER);
 		return;
@@ -332,8 +333,8 @@ static u32 intel_dp_aux_vesa_get_backlight(struct intel_connector *connector, en
 	if (!intel_dp_aux_vesa_backlight_dpcd_mode(connector))
 		return connector->panel.backlight.max;
 
-	if (drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
-			     &read_val, sizeof(read_val)) < 0) {
+	if (drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB, &read_val,
+			     sizeof(read_val)) != sizeof(read_val)) {
 		drm_dbg_kms(&i915->drm, "Failed to read DPCD register 0x%x\n",
 			    DP_EDP_BACKLIGHT_BRIGHTNESS_MSB);
 		return 0;
@@ -365,8 +366,8 @@ intel_dp_aux_vesa_set_backlight(const struct drm_connector_state *conn_state,
 		vals[0] = (level & 0xFF00) >> 8;
 		vals[1] = (level & 0xFF);
 	}
-	if (drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
-			      vals, sizeof(vals)) < 0) {
+	if (drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB, vals,
+			      sizeof(vals)) != sizeof(vals)) {
 		drm_dbg_kms(&i915->drm,
 			    "Failed to write aux backlight level\n");
 		return;
@@ -401,9 +402,8 @@ intel_dp_aux_vesa_enable_backlight(const struct intel_crtc_state *crtc_state,
 		new_dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
 		new_dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
 
-		if (drm_dp_dpcd_writeb(&intel_dp->aux,
-				       DP_EDP_PWMGEN_BIT_COUNT,
-				       pwmgen_bit_count) < 0)
+		if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_PWMGEN_BIT_COUNT,
+				       pwmgen_bit_count) != 1)
 			drm_dbg_kms(&i915->drm,
 				    "Failed to write aux pwmgen bit count\n");
 
@@ -424,11 +424,9 @@ intel_dp_aux_vesa_enable_backlight(const struct intel_crtc_state *crtc_state,
 	}
 
 	if (new_dpcd_buf != dpcd_buf) {
-		if (drm_dp_dpcd_writeb(&intel_dp->aux,
-			DP_EDP_BACKLIGHT_MODE_SET_REGISTER, new_dpcd_buf) < 0) {
-			drm_dbg_kms(&i915->drm,
-				    "Failed to write aux backlight mode\n");
-		}
+		if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
+				       new_dpcd_buf) != 1)
+			drm_dbg_kms(&i915->drm, "Failed to write aux backlight mode\n");
 	}
 
 	intel_dp_aux_vesa_set_backlight(conn_state, level);
@@ -519,8 +517,7 @@ static u32 intel_dp_aux_vesa_calc_max_backlight(struct intel_connector *connecto
 	}
 
 	drm_dbg_kms(&i915->drm, "Using eDP pwmgen bit count of %d\n", pn);
-	if (drm_dp_dpcd_writeb(&intel_dp->aux,
-			       DP_EDP_PWMGEN_BIT_COUNT, pn) < 0) {
+	if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_PWMGEN_BIT_COUNT, pn) != 1) {
 		drm_dbg_kms(&i915->drm,
 			    "Failed to write aux pwmgen bit count\n");
 		return max_backlight;