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Mon, 11 May 2026 06:55:44 -0700 (PDT) From: Stepan Ionichev To: jic23@kernel.org Cc: dlechner@baylibre.com, nuno.sa@analog.com, andy@kernel.org, gregkh@linuxfoundation.org, hcazarim@yahoo.com, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, sozdayvek@gmail.com Subject: [PATCH v2] iio: gyro: bmg160: wait full startup time after mode change at probe Date: Mon, 11 May 2026 11:40:20 +0500 Message-Id: <20260511064020.362-1-sozdayvek@gmail.com> X-Mailer: git-send-email 2.33.0.windows.2 In-Reply-To: <20260511062755.30-1-sozdayvek@gmail.com> References: <20260511062755.30-1-sozdayvek@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit bmg160_chip_init() calls bmg160_set_mode(BMG160_MODE_NORMAL) and then waits only 500-1000 us. Per the BMG160 datasheet (BST-BMG160-DS000-07 Rev. 1.0, May 2013), the start-up and wake-up times (tsu, twusm) are 30 ms. The same file already waits BMG160_MAX_STARTUP_TIME_MS (80 ms) in bmg160_runtime_resume() after the same set_mode(NORMAL) operation. The 500 us value at probe was likely a unit mix-up; the old comment said "500 ms" while the code used microseconds. Reuse the same constant via msleep() and add a code comment explaining the datasheet basis for the wait. Without this, register writes that follow the mode change can hit the chip before it is ready. Fixes: 22b46c45fb9b ("iio:gyro:bmg160 Gyro Sensor driver") Signed-off-by: Stepan Ionichev --- v2: - Use msleep() instead of msleep_interruptible() so the wait is not cut short by signals during probe (per Andy) - Add a code comment with the datasheet basis for the 80 ms wait (per Andy) drivers/iio/gyro/bmg160_core.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/iio/gyro/bmg160_core.c b/drivers/iio/gyro/bmg160_core.c index 38394b5f3..6d9019451 100644 --- a/drivers/iio/gyro/bmg160_core.c +++ b/drivers/iio/gyro/bmg160_core.c @@ -258,8 +258,14 @@ static int bmg160_chip_init(struct bmg160_data *data) if (ret < 0) return ret; - /* Wait upto 500 ms to be ready after changing mode */ - usleep_range(500, 1000); + /* + * Wait for the chip to be ready after switching to normal mode. + * The BMG160 datasheet (BST-BMG160-DS000-07 Rev. 1.0, May 2013) + * specifies a start-up / wake-up time (tsu, twusm) of 30 ms; use + * BMG160_MAX_STARTUP_TIME_MS (80 ms) as a safety margin, matching + * what bmg160_runtime_resume() already does. + */ + msleep(BMG160_MAX_STARTUP_TIME_MS); /* Set Bandwidth */ ret = bmg160_set_bw(data, BMG160_DEF_BW); -- 2.43.0