linux-kernel - [PATCH] drm: panel: himax-hx8279: avoid using an uninitialized variable

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Message-Id: <20250423163214.2276114-1-arnd@kernel.org>
Date: Wed, 23 Apr 2025 18:32:07 +0200
From: Arnd Bergmann <arnd@...nel.org>
To: Neil Armstrong <neil.armstrong@...aro.org>,
	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>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: Arnd Bergmann <arnd@...db.de>,
	Jessica Zhang <quic_jesszhan@...cinc.com>,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] drm: panel: himax-hx8279: avoid using an uninitialized variable

From: Arnd Bergmann <arnd@...db.de>

goa_even_valid is only initialized in one branch but not the other:

drivers/gpu/drm/panel/panel-himax-hx8279.c:838:6: error: variable 'goa_even_valid' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
  838 |         if (num_zero == ARRAY_SIZE(desc->goa_even_timing))
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/panel/panel-himax-hx8279.c:842:23: note: uninitialized use occurs here
  842 |         if (goa_odd_valid != goa_even_valid)
      |                              ^~~~~~~~~~~~~~

Change the initialization to set it to the value of the condition instead.

Fixes: 38d42c261389 ("drm: panel: Add driver for Himax HX8279 DDIC panels")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/gpu/drm/panel/panel-himax-hx8279.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-himax-hx8279.c b/drivers/gpu/drm/panel/panel-himax-hx8279.c
index b48b350b62da..4f548430654a 100644
--- a/drivers/gpu/drm/panel/panel-himax-hx8279.c
+++ b/drivers/gpu/drm/panel/panel-himax-hx8279.c
@@ -835,8 +835,7 @@ static int hx8279_check_goa_config(struct hx8279 *hx, struct device *dev)
 			num_zero++;
 	}
 
-	if (num_zero == ARRAY_SIZE(desc->goa_even_timing))
-		goa_even_valid = false;
+	goa_even_valid = (num_zero != ARRAY_SIZE(desc->goa_even_timing));
 
 	/* Programming one without the other would make no sense! */
 	if (goa_odd_valid != goa_even_valid)
-- 
2.39.5