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Mon, 26 Jan 2026 09:35:01 -0800 (PST) Received: from saikiran-Yoga-Slim-7-14Q8X9 ([2402:e280:3d17:646:e23f:af76:8280:9d84]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-353f61292bdsm86787a91.6.2026.01.26.09.34.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Jan 2026 09:35:01 -0800 (PST) From: Saikiran To: linux-media@vger.kernel.org Cc: linux-arm-msm@vger.kernel.org, rfoss@kernel.org, todor.too@gmail.com, bryan.odonoghue@linaro.org, bod@kernel.org, vladimir.zapolskiy@linaro.org, hansg@kernel.org, sakari.ailus@linux.intel.com, mchehab@kernel.org, stable@vger.kernel.org, Saikiran Subject: [PATCH v3 2/3] media: i2c: ov02c10: Correct power-on sequence and timing Date: Mon, 26 Jan 2026 23:04:43 +0530 Message-ID: <20260126173444.10228-3-bjsaikiran@gmail.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260126173444.10228-1-bjsaikiran@gmail.com> References: <20260126173444.10228-1-bjsaikiran@gmail.com> Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 1. Assert XSHUTDOWN (reset) for 10ms (T1 >= 5ms) before enabling power. 2. Enable regulators and wait 20ms for ramp-up stabilization. 3. Enable clock and wait 10ms for stabilization. 4. De-assert XSHUTDOWN. 5. Wait 20ms (T2 >= 20ms) for sensor boot before I2C access. 6. Perform software reset (0x0103) to ensure clean state. This eliminates potential race conditions and stability issues during cold boot initialization. Tested-on: Lenovo Yoga Slim 7x (Snapdragon X Elite) Fixes: 44f8901 ("media: i2c: add OmniVision OV02C10 sensor driver") Cc: stable@vger.kernel.org Signed-off-by: Saikiran --- drivers/media/i2c/ov02c10.c | 57 ++++++++++++++++++++++++++++++------- 1 file changed, 46 insertions(+), 11 deletions(-) diff --git a/drivers/media/i2c/ov02c10.c b/drivers/media/i2c/ov02c10.c index fa7cc48b769a..ba8bbb4f433a 100644 --- a/drivers/media/i2c/ov02c10.c +++ b/drivers/media/i2c/ov02c10.c @@ -22,6 +22,8 @@ #define OV02C10_CHIP_ID 0x5602 #define OV02C10_REG_STREAM_CONTROL CCI_REG8(0x0100) +#define OV02C10_REG_SOFTWARE_RESET CCI_REG8(0x0103) +#define OV02C10_SOFTWARE_RESET_TRIGGER 0x01 #define OV02C10_REG_HTS CCI_REG16(0x380c) @@ -616,6 +618,13 @@ static int ov02c10_enable_streams(struct v4l2_subdev *sd, if (ret) goto out; + /* + * Delay before streaming: + * Give the sensor time to process all the register writes and internal + * calibration before we assert the STREAM_ON bit. + */ + usleep_range(2000, 2500); + ret = cci_write(ov02c10->regmap, OV02C10_REG_STREAM_CONTROL, 1, NULL); out: if (ret) @@ -660,13 +669,13 @@ static int ov02c10_power_off(struct device *dev) struct v4l2_subdev *sd = dev_get_drvdata(dev); struct ov02c10 *ov02c10 = to_ov02c10(sd); - gpiod_set_value_cansleep(ov02c10->reset, 1); + if (ov02c10->reset) + gpiod_set_value_cansleep(ov02c10->reset, 1); + clk_disable_unprepare(ov02c10->img_clk); regulator_bulk_disable(ARRAY_SIZE(ov02c10_supply_names), ov02c10->supplies); - clk_disable_unprepare(ov02c10->img_clk); - return 0; } @@ -676,27 +685,53 @@ static int ov02c10_power_on(struct device *dev) struct ov02c10 *ov02c10 = to_ov02c10(sd); int ret; - ret = clk_prepare_enable(ov02c10->img_clk); - if (ret < 0) { - dev_err(dev, "failed to enable imaging clock: %d", ret); - return ret; + if (ov02c10->reset) { + gpiod_set_value_cansleep(ov02c10->reset, 1); + usleep_range(10000, 11000); } ret = regulator_bulk_enable(ARRAY_SIZE(ov02c10_supply_names), ov02c10->supplies); if (ret < 0) { dev_err(dev, "failed to enable regulators: %d", ret); - clk_disable_unprepare(ov02c10->img_clk); return ret; } + /* Allow PMIC to ramp and stabilize */ + usleep_range(20000, 22000); + + ret = clk_prepare_enable(ov02c10->img_clk); + if (ret < 0) { + dev_err(dev, "failed to enable imaging clock: %d", ret); + regulator_bulk_disable(ARRAY_SIZE(ov02c10_supply_names), + ov02c10->supplies); + return ret; + } + + /* Let the clock stabilise */ + usleep_range(10000, 11000); + + /* Release hardware reset */ if (ov02c10->reset) { - /* Assert reset for at least 2ms on back to back off-on */ - usleep_range(2000, 2200); gpiod_set_value_cansleep(ov02c10->reset, 0); - usleep_range(5000, 5100); + /* + * Wait for sensor microcontroller to stabilize after reset release. + * 20ms prevents black frames during rapid power cycling. + */ + usleep_range(20000, 22000); + } + + /* Perform software reset to ensure clean state */ + ret = cci_write(ov02c10->regmap, OV02C10_REG_SOFTWARE_RESET, + OV02C10_SOFTWARE_RESET_TRIGGER, NULL); + if (ret) { + dev_err(dev, "failed to send software reset: %d", ret); + return ret; } + /* Wait for software reset to complete */ + usleep_range(5000, 5500); + return 0; } -- 2.51.0