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drm/panel: himax-hx8279: Always initialize goa_{even,odd}_valid in hx8279_check_goa_config()

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Clang warns (or errors with CONFIG_WERROR=y):

  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)
        |                              ^~~~~~~~~~~~~~
  drivers/gpu/drm/panel/panel-himax-hx8279.c:838:2: note: remove the 'if' if its condition is always true
    838 |         if (num_zero == ARRAY_SIZE(desc->goa_even_timing))
        |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    839 |                 goa_even_valid = false;
  drivers/gpu/drm/panel/panel-himax-hx8279.c:818:36: note: initialize the variable 'goa_even_valid' to silence this warning
    818 |         bool goa_odd_valid, goa_even_valid;
        |                                           ^
        |                                            = 0

Even though only the even valid variable gets flagged, both valid
variables appear to have the same issue of possibly being used
uninitialized if the if statement initializing them to false is not
taken.

Turn the if statement then variable assignment into a single variable
assignment, which states that the configuration is valid when there are
not all zeros, clearing up the warning since the variable will always be
initialized.

Fixes: 38d42c2613 ("drm: panel: Add driver for Himax HX8279 DDIC panels")
Suggested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250423-panel-himax-hx8279-fix-sometimes-uninitialized-v2-1-fc501c6558d9@kernel.org
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250423-panel-himax-hx8279-fix-sometimes-uninitialized-v2-1-fc501c6558d9@kernel.org
This commit is contained in:
Nathan Chancellor 2025-04-23 10:41:41 -07:00 committed by Neil Armstrong
parent ef6517ac5c
commit 0228687423
1 changed files with 2 additions and 4 deletions
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6
drivers/gpu/drm/panel/panel-himax-hx8279.c
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@ -825,8 +825,7 @@ static int hx8279_check_goa_config(struct hx8279 *hx, struct device *dev)
num_zero++;
}
if (num_zero == ARRAY_SIZE(desc->goa_odd_timing))
goa_odd_valid = false;
goa_odd_valid = (num_zero != ARRAY_SIZE(desc->goa_odd_timing));
/* Up to 3 zeroes is a valid config. Check them all. */
num_zero = 1;
@ -835,8 +834,7 @@ 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)