From: Brigham Campbell <me@brighamcampbell.com>
Date: Thu, 31 Jul 2025 03:23:41 +0000 (-0600)
Subject: drm/panel: novatek-nt35560: Fix invalid return value
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=125459e19ec654924e472f3ff5aeea40358dbebf;p=users%2Fhch%2Fmisc.git

drm/panel: novatek-nt35560: Fix invalid return value

Fix bug in nt35560_set_brightness() which causes the function to
erroneously report an error. mipi_dsi_dcs_write() returns either a
negative value when an error occurred or a positive number of bytes
written when no error occurred. The buggy code reports an error under
either condition.

Fixes: 8152c2bfd780 ("drm/panel: Add driver for Sony ACX424AKP panel")
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Brigham Campbell <me@brighamcampbell.com>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250731032343.1258366-2-me@brighamcampbell.com
---

diff --git a/drivers/gpu/drm/panel/panel-novatek-nt35560.c b/drivers/gpu/drm/panel/panel-novatek-nt35560.c
index 98f0782c8411..17898a29efe8 100644
--- a/drivers/gpu/drm/panel/panel-novatek-nt35560.c
+++ b/drivers/gpu/drm/panel/panel-novatek-nt35560.c
@@ -161,7 +161,7 @@ static int nt35560_set_brightness(struct backlight_device *bl)
 		par = 0x00;
 		ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_WRITE_CONTROL_DISPLAY,
 					 &par, 1);
-		if (ret) {
+		if (ret < 0) {
 			dev_err(nt->dev, "failed to disable display backlight (%d)\n", ret);
 			return ret;
 		}