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([2a01:e0a:3d9:2080:2835:c2f4:c226:77dd]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-39efa43d006sm19124430f8f.56.2025.04.23.06.50.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 23 Apr 2025 06:50:30 -0700 (PDT) Message-ID: Date: Wed, 23 Apr 2025 15:50:29 +0200 Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Reply-To: neil.armstrong@linaro.org Subject: Re: [PATCH] drm/panel: himax-hx8279: Initialize goa_{even,odd}_valid in hx8279_check_goa_config() From: Neil Armstrong To: Nathan Chancellor , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann Cc: Jessica Zhang , AngeloGioacchino Del Regno , dri-devel@lists.freedesktop.org, llvm@lists.linux.dev, patches@lists.linux.dev References: <20250422-panel-himax-hx8279-fix-sometimes-uninitialized-v1-1-614dba12b30d@kernel.org> Content-Language: en-US, fr Autocrypt: addr=neil.armstrong@linaro.org; keydata= xsBNBE1ZBs8BCAD78xVLsXPwV/2qQx2FaO/7mhWL0Qodw8UcQJnkrWmgTFRobtTWxuRx8WWP GTjuhvbleoQ5Cxjr+v+1ARGCH46MxFP5DwauzPekwJUD5QKZlaw/bURTLmS2id5wWi3lqVH4 BVF2WzvGyyeV1o4RTCYDnZ9VLLylJ9bneEaIs/7cjCEbipGGFlfIML3sfqnIvMAxIMZrvcl9 qPV2k+KQ7q+aXavU5W+yLNn7QtXUB530Zlk/d2ETgzQ5FLYYnUDAaRl+8JUTjc0CNOTpCeik 80TZcE6f8M76Xa6yU8VcNko94Ck7iB4vj70q76P/J7kt98hklrr85/3NU3oti3nrIHmHABEB AAHNKk5laWwgQXJtc3Ryb25nIDxuZWlsLmFybXN0cm9uZ0BsaW5hcm8ub3JnPsLAkQQTAQoA OwIbIwULCQgHAwUVCgkICwUWAgMBAAIeAQIXgBYhBInsPQWERiF0UPIoSBaat7Gkz/iuBQJk Q5wSAhkBAAoJEBaat7Gkz/iuyhMIANiD94qDtUTJRfEW6GwXmtKWwl/mvqQtaTtZID2dos04 YqBbshiJbejgVJjy+HODcNUIKBB3PSLaln4ltdsV73SBcwUNdzebfKspAQunCM22Mn6FBIxQ GizsMLcP/0FX4en9NaKGfK6ZdKK6kN1GR9YffMJd2P08EO8mHowmSRe/ExAODhAs9W7XXExw UNCY4pVJyRPpEhv373vvff60bHxc1k/FF9WaPscMt7hlkbFLUs85kHtQAmr8pV5Hy9ezsSRa GzJmiVclkPc2BY592IGBXRDQ38urXeM4nfhhvqA50b/nAEXc6FzqgXqDkEIwR66/Gbp0t3+r yQzpKRyQif3OwE0ETVkGzwEIALyKDN/OGURaHBVzwjgYq+ZtifvekdrSNl8TIDH8g1xicBYp QTbPn6bbSZbdvfeQPNCcD4/EhXZuhQXMcoJsQQQnO4vwVULmPGgtGf8PVc7dxKOeta+qUh6+ SRh3vIcAUFHDT3f/Zdspz+e2E0hPV2hiSvICLk11qO6cyJE13zeNFoeY3ggrKY+IzbFomIZY 4yG6xI99NIPEVE9lNBXBKIlewIyVlkOaYvJWSV+p5gdJXOvScNN1epm5YHmf9aE2ZjnqZGoM Mtsyw18YoX9BqMFInxqYQQ3j/HpVgTSvmo5ea5qQDDUaCsaTf8UeDcwYOtgI8iL4oHcsGtUX oUk33HEAEQEAAcLAXwQYAQIACQUCTVkGzwIbDAAKCRAWmrexpM/4rrXiB/sGbkQ6itMrAIfn M7IbRuiSZS1unlySUVYu3SD6YBYnNi3G5EpbwfBNuT3H8//rVvtOFK4OD8cRYkxXRQmTvqa3 3eDIHu/zr1HMKErm+2SD6PO9umRef8V82o2oaCLvf4WeIssFjwB0b6a12opuRP7yo3E3gTCS KmbUuLv1CtxKQF+fUV1cVaTPMyT25Od+RC1K+iOR0F54oUJvJeq7fUzbn/KdlhA8XPGzwGRy 4zcsPWvwnXgfe5tk680fEKZVwOZKIEuJC3v+/yZpQzDvGYJvbyix0lHnrCzq43WefRHI5XTT QbM0WUIBIcGmq38+OgUsMYu4NzLu7uZFAcmp6h8g Organization: Linaro In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 23/04/2025 15:45, Neil Armstrong wrote: > On 22/04/2025 23:20, Nathan Chancellor wrote: >> 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. >> >> Initialize both values to true to clear up the warning and remove any >> possibility of encountering undefined behavior. >> >> Fixes: 38d42c261389 ("drm: panel: Add driver for Himax HX8279 DDIC panels") >> Signed-off-by: Nathan Chancellor >> --- >>   drivers/gpu/drm/panel/panel-himax-hx8279.c | 2 +- >>   1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/drm/panel/panel-himax-hx8279.c b/drivers/gpu/drm/panel/panel-himax-hx8279.c >> index b48b350b62da..92f351e66c25 100644 >> --- a/drivers/gpu/drm/panel/panel-himax-hx8279.c >> +++ b/drivers/gpu/drm/panel/panel-himax-hx8279.c >> @@ -815,7 +815,7 @@ static int hx8279_check_gmux_config(struct hx8279 *hx, struct device *dev) >>   static int hx8279_check_goa_config(struct hx8279 *hx, struct device *dev) >>   { >>       const struct hx8279_panel_desc *desc = hx->desc; >> -    bool goa_odd_valid, goa_even_valid; >> +    bool goa_odd_valid = true, goa_even_valid = true; >>       int i, num_zero, num_clr = 0; >>       /* Up to 4 zero values is a valid configuration. Check them all. */ >> >> --- >> base-commit: dcbd5dcc956e2331414fd7020b4655df08deeb87 >> change-id: 20250422-panel-himax-hx8279-fix-sometimes-uninitialized-207354fb930c >> >> Best regards, > > Reviewed-by: Neil Armstrong I'll wait a few days until AngeloGioacchino Del Regno reviews it to be sure it's the right fix. Thanks, Neil