drm/panel: novatek-nt35560: Clean up driver

Update driver to use the "multi" variants of MIPI functions which
facilitate improved error handling and cleaner driver code.

Remove information from a comment which was made obsolete by commit
994ea40 ("drm/panel: Rename Sony ACX424 to Novatek NT35560"), which
determined that this driver supports the Novatek NT35560 panel
controller.

Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Brigham Campbell <me@brighamcampbell.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20250731032343.1258366-4-me@brighamcampbell.com

Author: brighamcampbell

drivers/gpu/drm/panel/panel-novatek-nt35560.c

@@ -148,24 +148,20 @@ static inline struct nt35560 *panel_to_nt35560(struct drm_panel *panel)
 static int nt35560_set_brightness(struct backlight_device *bl)
 {
 	struct nt35560 *nt = bl_get_data(bl);
-	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
-	int period_ns = 1023;
+	struct mipi_dsi_multi_context dsi_ctx = {
+		.dsi = to_mipi_dsi_device(nt->dev)
+	};
 	int duty_ns = bl->props.brightness;
+	int period_ns = 1023;
 	u8 pwm_ratio;
 	u8 pwm_div;
-	u8 par;
-	int ret;
 
 	if (backlight_is_blank(bl)) {
 		/* Disable backlight */
-		par = 0x00;
-		ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_WRITE_CONTROL_DISPLAY,
-					 &par, 1);
-		if (ret < 0) {
-			dev_err(nt->dev, "failed to disable display backlight (%d)\n", ret);
-			return ret;
-		}
-		return 0;
+		mipi_dsi_dcs_write_seq_multi(&dsi_ctx,
+					     MIPI_DCS_WRITE_CONTROL_DISPLAY,
+					     0x00);
+		return dsi_ctx.accum_err;
 	}
 
 	/* Calculate the PWM duty cycle in n/256's */
@@ -176,12 +172,6 @@ static int nt35560_set_brightness(struct backlight_device *bl)
 
 	/* Set up PWM dutycycle ONE byte (differs from the standard) */
 	dev_dbg(nt->dev, "calculated duty cycle %02x\n", pwm_ratio);
-	ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
-				 &pwm_ratio, 1);
-	if (ret < 0) {
-		dev_err(nt->dev, "failed to set display PWM ratio (%d)\n", ret);
-		return ret;
-	}
 
 	/*
 	 * Sequence to write PWMDIV:
@@ -192,46 +182,23 @@ static int nt35560_set_brightness(struct backlight_device *bl)
 	 *	0x22		PWMDIV
 	 *	0x7F		0xAA   CMD2 page 1 lock
 	 */
-	par = 0xaa;
-	ret = mipi_dsi_dcs_write(dsi, 0xf3, &par, 1);
-	if (ret < 0) {
-		dev_err(nt->dev, "failed to unlock CMD 2 (%d)\n", ret);
-		return ret;
-	}
-	par = 0x01;
-	ret = mipi_dsi_dcs_write(dsi, 0x00, &par, 1);
-	if (ret < 0) {
-		dev_err(nt->dev, "failed to enter page 1 (%d)\n", ret);
-		return ret;
-	}
-	par = 0x01;
-	ret = mipi_dsi_dcs_write(dsi, 0x7d, &par, 1);
-	if (ret < 0) {
-		dev_err(nt->dev, "failed to disable MTP reload (%d)\n", ret);
-		return ret;
-	}
-	ret = mipi_dsi_dcs_write(dsi, 0x22, &pwm_div, 1);
-	if (ret < 0) {
-		dev_err(nt->dev, "failed to set PWM divisor (%d)\n", ret);
-		return ret;
-	}
-	par = 0xaa;
-	ret = mipi_dsi_dcs_write(dsi, 0x7f, &par, 1);
-	if (ret < 0) {
-		dev_err(nt->dev, "failed to lock CMD 2 (%d)\n", ret);
-		return ret;
-	}
+	mipi_dsi_dcs_write_var_seq_multi(&dsi_ctx,
+					 MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
+					 pwm_ratio);
+
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf3, 0xaa);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x00, 0x01);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x7d, 0x01);
+
+	mipi_dsi_dcs_write_var_seq_multi(&dsi_ctx, 0x22, pwm_div);
+
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x7f, 0xaa);
 
 	/* Enable backlight */
-	par = 0x24;
-	ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_WRITE_CONTROL_DISPLAY,
-				 &par, 1);
-	if (ret < 0) {
-		dev_err(nt->dev, "failed to enable display backlight (%d)\n", ret);
-		return ret;
-	}
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, MIPI_DCS_WRITE_CONTROL_DISPLAY,
+				     0x24);
 
-	return 0;
+	return dsi_ctx.accum_err;
 }
 
 static const struct backlight_ops nt35560_bl_ops = {
@@ -244,32 +211,23 @@ static const struct backlight_properties nt35560_bl_props = {
 	.max_brightness = 1023,
 };
 
-static int nt35560_read_id(struct nt35560 *nt)
+static void nt35560_read_id(struct mipi_dsi_multi_context *dsi_ctx)
 {
-	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
+	struct device dev = dsi_ctx->dsi->dev;
 	u8 vendor, version, panel;
 	u16 val;
-	int ret;
 
-	ret = mipi_dsi_dcs_read(dsi, NT35560_DCS_READ_ID1, &vendor, 1);
-	if (ret < 0) {
-		dev_err(nt->dev, "could not vendor ID byte\n");
-		return ret;
-	}
-	ret = mipi_dsi_dcs_read(dsi, NT35560_DCS_READ_ID2, &version, 1);
-	if (ret < 0) {
-		dev_err(nt->dev, "could not read device version byte\n");
-		return ret;
-	}
-	ret = mipi_dsi_dcs_read(dsi, NT35560_DCS_READ_ID3, &panel, 1);
-	if (ret < 0) {
-		dev_err(nt->dev, "could not read panel ID byte\n");
-		return ret;
-	}
+	mipi_dsi_dcs_read_multi(dsi_ctx, NT35560_DCS_READ_ID1, &vendor, 1);
+	mipi_dsi_dcs_read_multi(dsi_ctx, NT35560_DCS_READ_ID2, &version, 1);
+	mipi_dsi_dcs_read_multi(dsi_ctx, NT35560_DCS_READ_ID3, &panel, 1);
+
+	if (dsi_ctx->accum_err < 0)
+		return;
 
 	if (vendor == 0x00) {
-		dev_err(nt->dev, "device vendor ID is zero\n");
-		return -ENODEV;
+		dev_err(&dev, "device vendor ID is zero\n");
+		dsi_ctx->accum_err = -ENODEV;
+		return;
 	}
 
 	val = (vendor << 8) | panel;
@@ -278,16 +236,16 @@ static int nt35560_read_id(struct nt35560 *nt)
 	case DISPLAY_SONY_ACX424AKP_ID2:
 	case DISPLAY_SONY_ACX424AKP_ID3:
 	case DISPLAY_SONY_ACX424AKP_ID4:
-		dev_info(nt->dev, "MTP vendor: %02x, version: %02x, panel: %02x\n",
+		dev_info(&dev,
+			 "MTP vendor: %02x, version: %02x, panel: %02x\n",
 			 vendor, version, panel);
 		break;
 	default:
-		dev_info(nt->dev, "unknown vendor: %02x, version: %02x, panel: %02x\n",
+		dev_info(&dev,
+			 "unknown vendor: %02x, version: %02x, panel: %02x\n",
 			 vendor, version, panel);
 		break;
 	}
-
-	return 0;
 }
 
 static int nt35560_power_on(struct nt35560 *nt)
@@ -322,92 +280,56 @@ static void nt35560_power_off(struct nt35560 *nt)
 static int nt35560_prepare(struct drm_panel *panel)
 {
 	struct nt35560 *nt = panel_to_nt35560(panel);
-	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
-	const u8 mddi = 3;
+	struct mipi_dsi_multi_context dsi_ctx = {
+		.dsi = to_mipi_dsi_device(nt->dev)
+	};
 	int ret;
 
 	ret = nt35560_power_on(nt);
 	if (ret)
 		return ret;
 
-	ret = nt35560_read_id(nt);
-	if (ret) {
-		dev_err(nt->dev, "failed to read panel ID (%d)\n", ret);
-		goto err_power_off;
-	}
+	nt35560_read_id(&dsi_ctx);
 
-	/* Enabe tearing mode: send TE (tearing effect) at VBLANK */
-	ret = mipi_dsi_dcs_set_tear_on(dsi,
+	/* Enable tearing mode: send TE (tearing effect) at VBLANK */
+	mipi_dsi_dcs_set_tear_on_multi(&dsi_ctx,
 				       MIPI_DSI_DCS_TEAR_MODE_VBLANK);
-	if (ret) {
-		dev_err(nt->dev, "failed to enable vblank TE (%d)\n", ret);
-		goto err_power_off;
-	}
 
 	/*
 	 * Set MDDI
 	 *
 	 * This presumably deactivates the Qualcomm MDDI interface and
 	 * selects DSI, similar code is found in other drivers such as the
-	 * Sharp LS043T1LE01 which makes us suspect that this panel may be
-	 * using a Novatek NT35565 or similar display driver chip that shares
-	 * this command. Due to the lack of documentation we cannot know for
-	 * sure.
+	 * Sharp LS043T1LE01.
 	 */
-	ret = mipi_dsi_dcs_write(dsi, NT35560_DCS_SET_MDDI,
-				 &mddi, sizeof(mddi));
-	if (ret < 0) {
-		dev_err(nt->dev, "failed to set MDDI (%d)\n", ret);
-		goto err_power_off;
-	}
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, NT35560_DCS_SET_MDDI, 3);
 
-	/* Exit sleep mode */
-	ret = mipi_dsi_dcs_exit_sleep_mode(dsi);
-	if (ret) {
-		dev_err(nt->dev, "failed to exit sleep mode (%d)\n", ret);
-		goto err_power_off;
-	}
-	msleep(140);
+	mipi_dsi_dcs_exit_sleep_mode_multi(&dsi_ctx);
+	mipi_dsi_msleep(&dsi_ctx, 140);
 
-	ret = mipi_dsi_dcs_set_display_on(dsi);
-	if (ret) {
-		dev_err(nt->dev, "failed to turn display on (%d)\n", ret);
-		goto err_power_off;
-	}
+	mipi_dsi_dcs_set_display_on_multi(&dsi_ctx);
 	if (nt->video_mode) {
-		/* In video mode turn peripheral on */
-		ret = mipi_dsi_turn_on_peripheral(dsi);
-		if (ret) {
-			dev_err(nt->dev, "failed to turn on peripheral\n");
-			goto err_power_off;
-		}
+		mipi_dsi_turn_on_peripheral_multi(&dsi_ctx);
 	}
 
-	return 0;
-
-err_power_off:
-	nt35560_power_off(nt);
-	return ret;
+	if (dsi_ctx.accum_err < 0)
+		nt35560_power_off(nt);
+	return dsi_ctx.accum_err;
 }
 
 static int nt35560_unprepare(struct drm_panel *panel)
 {
 	struct nt35560 *nt = panel_to_nt35560(panel);
-	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
-	int ret;
+	struct mipi_dsi_multi_context dsi_ctx = {
+		.dsi = to_mipi_dsi_device(nt->dev)
+	};
 
-	ret = mipi_dsi_dcs_set_display_off(dsi);
-	if (ret) {
-		dev_err(nt->dev, "failed to turn display off (%d)\n", ret);
-		return ret;
-	}
+	mipi_dsi_dcs_set_display_off_multi(&dsi_ctx);
+	mipi_dsi_dcs_enter_sleep_mode_multi(&dsi_ctx);
+
+	if (dsi_ctx.accum_err < 0)
+		return dsi_ctx.accum_err;
 
-	/* Enter sleep mode */
-	ret = mipi_dsi_dcs_enter_sleep_mode(dsi);
-	if (ret) {
-		dev_err(nt->dev, "failed to enter sleep mode (%d)\n", ret);
-		return ret;
-	}
 	msleep(85);
 
 	nt35560_power_off(nt);