drm/panel: sitronix-st7789v: improve error handling

Improve error handling in the probe routine, so that probe
defer errors are captured in /sys/kernel/debug/devices_deferred
Reviewed-by: Michael Riesch <michael.riesch@wolfvision.net>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230714013756.1546769-8-sre@kernel.org

drivers/gpu/drm/panel/panel-sitronix-st7789v.c

@@ -348,32 +348,33 @@ static const struct drm_panel_funcs st7789v_drm_funcs = {
 
 static int st7789v_probe(struct spi_device *spi)
 {
+	struct device *dev = &spi->dev;
 	struct st7789v *ctx;
 	int ret;
 
-	ctx = devm_kzalloc(&spi->dev, sizeof(*ctx), GFP_KERNEL);
+	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
 	if (!ctx)
 		return -ENOMEM;
 
 	spi_set_drvdata(spi, ctx);
 	ctx->spi = spi;
 
-	drm_panel_init(&ctx->panel, &spi->dev, &st7789v_drm_funcs,
+	drm_panel_init(&ctx->panel, dev, &st7789v_drm_funcs,
 		       DRM_MODE_CONNECTOR_DPI);
 
-	ctx->power = devm_regulator_get(&spi->dev, "power");
-	if (IS_ERR(ctx->power))
-		return PTR_ERR(ctx->power);
+	ctx->power = devm_regulator_get(dev, "power");
+	ret = PTR_ERR_OR_ZERO(ctx->power);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to get regulator\n");
 
-	ctx->reset = devm_gpiod_get_optional(&spi->dev, "reset", GPIOD_OUT_LOW);
-	if (IS_ERR(ctx->reset)) {
-		dev_err(&spi->dev, "Couldn't get our reset line\n");
-		return PTR_ERR(ctx->reset);
-	}
+	ctx->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
+	ret = PTR_ERR_OR_ZERO(ctx->reset);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to get reset line\n");
 
 	ret = drm_panel_of_backlight(&ctx->panel);
 	if (ret)
-		return ret;
+		return dev_err_probe(dev, ret, "Failed to get backlight\n");
 
 	drm_panel_add(&ctx->panel);