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([178.197.219.123]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-afcdcfcb2bbsm556869166b.77.2025.08.17.01.48.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 17 Aug 2025 01:48:35 -0700 (PDT) From: Krzysztof Kozlowski To: Sakari Ailus , Dave Stevenson , Mauro Carvalho Chehab , Leon Luo , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Krzysztof Kozlowski Subject: [PATCH] media: i2c: imx: Add note to prevent buggy code re-use Date: Sun, 17 Aug 2025 10:48:25 +0200 Message-ID: <20250817084824.31117-2-krzysztof.kozlowski@linaro.org> X-Mailer: git-send-email 2.48.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2304; i=krzysztof.kozlowski@linaro.org; h=from:subject; bh=C19dFe425N3sGthJuclaFaN06VJyYYm5nphRa1kdApw=; b=owEBbQKS/ZANAwAKAcE3ZuaGi4PXAcsmYgBooZdYJZC4ruittkd5WoUdoy+AE5pgPlKyB2Vfc 1ud7LkshleJAjMEAAEKAB0WIQTd0mIoPREbIztuuKjBN2bmhouD1wUCaKGXWAAKCRDBN2bmhouD 151fD/4zS+PfBf/INbbVJfR+nLjpqsA3lHWNA92UCsFn+RBh/90t/tD+SYFtaxBWpts7lYyqVbL RCsord/BDDdoBor9K8n/2TCGV0H4r3BgLSFlMIYGutnO7L8v62pTmI9uL5g23lBPG3cWFDdg8Ab EwiA9EOwlgJt8cZQhhRrpsPjoCTLLR9h5HkKFYtljrquFoPILNS9mhD1uCsZ5chewfHQLiS1V2P +T+hBK8W+XV44nmJYhxU7Jxh7Q8aA4uip5I7UEeEasKTALWxA1iYDQRpdHfCLZ9RYzpbz2vx9u+ 2rIv4VqZf1MnaJFMF6n1fZeMGPbVhB/E2wqWxDqcYiLGSffw9cAnYZ7qi69vOFr8y4+DrZfxa6M 78zOKr68hLy1fz2sNAxdXsiSvREbXb3ot62iGIHCGZcy5VDwdU+tNd0gi93DnFZh5DW1Z1HU2oY kSfiK0OidZVclm8DbNv9JkiHI06XlN0W+oelDhmjHInN0dhMQkVJmD8YmnfBkEejWrXkI+riiob vZDq9D2ZnxUqefRNoJGrmZMhDE+G5+GJKO00eQN6z4SCHMEQ+RSVnPSf7c7WDGAT5K7K3siDxDO LM3qkqXhmZWLTVO9vawGWtHRhnCPUCXfo9BvDG+vK4pYfCMAafgQC9EaivrPd7ha+ew9K647BTA ovqaFMmTeqUu/6A== X-Developer-Key: i=krzysztof.kozlowski@linaro.org; a=openpgp; fpr=9BD07E0E0C51F8D59677B7541B93437D3B41629B Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Multiple Sony IMX sensor drivers have mixed up logical and line level for XCLR signal. They call it a reset signal (it indeed behaves like that), but drivers assert the reset to operate which is clearly incorrect and relies on incorrect DTS. People in discussions copy existing poor code and claim they can repeat same mistake, so add a note to prevent that. Signed-off-by: Krzysztof Kozlowski --- drivers/media/i2c/imx219.c | 4 ++++ drivers/media/i2c/imx274.c | 2 ++ drivers/media/i2c/imx334.c | 4 ++++ 3 files changed, 10 insertions(+) diff --git a/drivers/media/i2c/imx219.c b/drivers/media/i2c/imx219.c index 3b4f68543342..9857929a3321 100644 --- a/drivers/media/i2c/imx219.c +++ b/drivers/media/i2c/imx219.c @@ -1034,6 +1034,10 @@ static int imx219_power_on(struct device *dev) goto reg_off; } =20 + /* + * Note: Misinterpreation of reset assertion - do not re-use this code. + * XCLR pin is using incorrect (for reset signal) logical level. + */ gpiod_set_value_cansleep(imx219->reset_gpio, 1); usleep_range(IMX219_XCLR_MIN_DELAY_US, IMX219_XCLR_MIN_DELAY_US + IMX219_XCLR_DELAY_RANGE_US); diff --git a/drivers/media/i2c/imx274.c b/drivers/media/i2c/imx274.c index a2b824986027..385a3df74b66 100644 --- a/drivers/media/i2c/imx274.c +++ b/drivers/media/i2c/imx274.c @@ -826,6 +826,8 @@ static int imx274_start_stream(struct stimx274 *priv) * if rst =3D 0, keep it in reset; * if rst =3D 1, bring it out of reset. * + * Note: Misinterpreation of reset assertion - do not re-use this code. + * XCLR pin is using incorrect (for reset signal) logical level. */ static void imx274_reset(struct stimx274 *priv, int rst) { diff --git a/drivers/media/i2c/imx334.c b/drivers/media/i2c/imx334.c index 846b9928d4e8..72e020d1d335 100644 --- a/drivers/media/i2c/imx334.c +++ b/drivers/media/i2c/imx334.c @@ -1070,6 +1070,10 @@ static int imx334_power_on(struct device *dev) struct imx334 *imx334 =3D to_imx334(sd); int ret; =20 + /* + * Note: Misinterpreation of reset assertion - do not re-use this code. + * XCLR pin is using incorrect (for reset signal) logical level. + */ gpiod_set_value_cansleep(imx334->reset_gpio, 1); =20 ret =3D clk_prepare_enable(imx334->inclk); --=20 2.48.1