linux-kernel - [PATCH] drm/dp: Simplify return statement in drm_edp_backlight

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Message-Id: <20250818-drm-dp-helper-logically-dead-code-v1-1-080f76699c0f@gmail.com>
Date: Mon, 18 Aug 2025 13:25:18 +0800
From: Nai-Chen Cheng <bleach1827@...il.com>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 linux-kernel-mentees@...ts.linux.dev, Nai-Chen Cheng <bleach1827@...il.com>
Subject: [PATCH] drm/dp: Simplify return statement in
 drm_edp_backlight_enable

Remove dead code in error handling path. When drm_dp_dpcd_write_byte()
fails and ret < 0, the condition in "ret < 0 ? ret : -EIO" will always
be true, making -EIO unreachable.

Simplify by directly returning the error code from
drm_dp_dpcd_write_byte(), which provides more specific error information
for debugging.

Found by Coverity(CID 1649043).

Signed-off-by: Nai-Chen Cheng <bleach1827@...il.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index 1ecc3df7e3167d13636e194c4aab44ee8979aa11..b022ee136db2eb3b721ef918650525202dd22035 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -4079,7 +4079,7 @@ int drm_edp_backlight_enable(struct drm_dp_aux *aux, const struct drm_edp_backli
 	if (ret < 0) {
 		drm_dbg_kms(aux->drm_dev, "%s: Failed to write aux backlight mode: %d\n",
 			    aux->name, ret);
-		return ret < 0 ? ret : -EIO;
+		return ret;
 	}
 
 	ret = drm_edp_backlight_set_level(aux, bl, level);

---
base-commit: c17b750b3ad9f45f2b6f7e6f7f4679844244f0b9
change-id: 20250818-drm-dp-helper-logically-dead-code-b99252fbfcec

Best regards,
-- 
Nai-Chen Cheng <bleach1827@...il.com>