From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E8BC1398F8F; Wed, 3 Dec 2025 16:58:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764781117; cv=none; b=ezgw2hrCJ05KwKzrjerqcqQixrvs0dHDsasWUOk5kOX66GmoaiE2ZLm14PEvmBCPRWdTFeINAtAFadvJRE43NH+b+6fZazn075o+u9bbalPGc8Mi8fkFwxJRErUEwmkiyOg63OSZgzEAgkcXgzxLcHcFvLQN5lLCoc1IADAINlo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764781117; c=relaxed/simple; bh=VryIaiU4V0fvhmisUtSgQ27c1ZKzA4XCJenAKDA01Dc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=nene5ELMnvdTQIKPRaqkY/GK8ONPWI9AGz+pfKFyz7KZPu81UosN34tX4ob3KSKBtevOeRbe1Y8C6Rz2h6UQF9wC9NeKveq102RM9iLhO/W0HNFwc0plAEp+vduietQkmsAFzrC6rwvELxgynsaAfaZisTOAV0Wy4B8NsU7sbUQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=EsX2C3Bq; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="EsX2C3Bq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4DA3BC4CEF5; Wed, 3 Dec 2025 16:58:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1764781115; bh=VryIaiU4V0fvhmisUtSgQ27c1ZKzA4XCJenAKDA01Dc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EsX2C3Bq61uNsOV2EoMNcv9kOi/wW47IBHoX6tNyOz4YDc+QJyTp8N+Mm+0esv+J8 fj2hPgaq6t4cZ/aSZWOCLkK9tU/393cFvWoMdlEIH2gEX0Jl8OI+/JtIHWTAWTGjGF eM4iMGGt4lmdiJpmt9xFM0JUJuQPYreYeNiMzeFs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mario Tesi , Lorenzo Bianconi , Jonathan Cameron , Sasha Levin Subject: [PATCH 6.6 21/93] iio: st_lsm6dsx: Fixed calibrated timestamp calculation Date: Wed, 3 Dec 2025 16:29:14 +0100 Message-ID: <20251203152337.296222759@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251203152336.494201426@linuxfoundation.org> References: <20251203152336.494201426@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mario Tesi [ Upstream commit 8abbf45fcda028c2c05ba38eb14ede9fa9e7341b ] The calibrated timestamp is calculated from the nominal value using the formula: ts_gain[ns] ≈ ts_sensitivity - (ts_trim_coeff * val) / 1000. The values of ts_sensitivity and ts_trim_coeff are not the same for all devices, so it is necessary to differentiate them based on the part name. For the correct values please consult the relevant AN. Fixes: cb3b6b8e1bc0 ("iio: imu: st_lsm6dsx: add odr calibration feature") Signed-off-by: Mario Tesi Acked-by: Lorenzo Bianconi Signed-off-by: Jonathan Cameron Signed-off-by: Sasha Levin --- drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h | 18 ++++++++++++++++++ drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c | 19 ++++++++----------- 2 files changed, 26 insertions(+), 11 deletions(-) diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h index c19237717e812..0f347684f6fc9 100644 --- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h @@ -190,6 +190,22 @@ struct st_lsm6dsx_fifo_ops { * @fifo_en: Hw timer FIFO enable register info (addr + mask). * @decimator: Hw timer FIFO decimator register info (addr + mask). * @freq_fine: Difference in % of ODR with respect to the typical. + * @ts_sensitivity: Nominal timestamp sensitivity. + * @ts_trim_coeff: Coefficient for calculating the calibrated timestamp gain. + * This coefficient comes into play when linearizing the formula + * used to calculate the calibrated timestamp (please see the + * relevant formula in the AN for the specific IMU). + * For example, in the case of LSM6DSO we have: + * + * 1 / (1 + x) ~= 1 - x (Taylor’s Series) + * ttrim[s] = 1 / (40000 * (1 + 0.0015 * val)) (from AN5192) + * ttrim[ns] ~= 25000 - 37.5 * val + * ttrim[ns] ~= 25000 - (37500 * val) / 1000 + * + * so, replacing ts_sensitivity = 25000 and + * ts_trim_coeff = 37500 + * + * ttrim[ns] ~= ts_sensitivity - (ts_trim_coeff * val) / 1000 */ struct st_lsm6dsx_hw_ts_settings { struct st_lsm6dsx_reg timer_en; @@ -197,6 +213,8 @@ struct st_lsm6dsx_hw_ts_settings { struct st_lsm6dsx_reg fifo_en; struct st_lsm6dsx_reg decimator; u8 freq_fine; + u16 ts_sensitivity; + u16 ts_trim_coeff; }; /** diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c index b6e6b1df8a618..6e42e0c659e0c 100644 --- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c @@ -77,8 +77,6 @@ #define ST_LSM6DSX_REG_WHOAMI_ADDR 0x0f -#define ST_LSM6DSX_TS_SENSITIVITY 25000UL /* 25us */ - static const struct iio_chan_spec st_lsm6dsx_acc_channels[] = { ST_LSM6DSX_CHANNEL_ACC(IIO_ACCEL, 0x28, IIO_MOD_X, 0), ST_LSM6DSX_CHANNEL_ACC(IIO_ACCEL, 0x2a, IIO_MOD_Y, 1), @@ -962,6 +960,8 @@ static const struct st_lsm6dsx_settings st_lsm6dsx_sensor_settings[] = { .mask = GENMASK(7, 6), }, .freq_fine = 0x63, + .ts_sensitivity = 25000, + .ts_trim_coeff = 37500, }, .shub_settings = { .page_mux = { @@ -1175,6 +1175,8 @@ static const struct st_lsm6dsx_settings st_lsm6dsx_sensor_settings[] = { .mask = GENMASK(7, 6), }, .freq_fine = 0x63, + .ts_sensitivity = 25000, + .ts_trim_coeff = 37500, }, .event_settings = { .enable_reg = { @@ -1350,6 +1352,8 @@ static const struct st_lsm6dsx_settings st_lsm6dsx_sensor_settings[] = { .mask = GENMASK(7, 6), }, .freq_fine = 0x4f, + .ts_sensitivity = 21701, + .ts_trim_coeff = 28212, }, .shub_settings = { .page_mux = { @@ -2243,20 +2247,13 @@ static int st_lsm6dsx_init_hw_timer(struct st_lsm6dsx_hw *hw) } /* calibrate timestamp sensitivity */ - hw->ts_gain = ST_LSM6DSX_TS_SENSITIVITY; + hw->ts_gain = ts_settings->ts_sensitivity; if (ts_settings->freq_fine) { err = regmap_read(hw->regmap, ts_settings->freq_fine, &val); if (err < 0) return err; - /* - * linearize the AN5192 formula: - * 1 / (1 + x) ~= 1 - x (Taylor’s Series) - * ttrim[s] = 1 / (40000 * (1 + 0.0015 * val)) - * ttrim[ns] ~= 25000 - 37.5 * val - * ttrim[ns] ~= 25000 - (37500 * val) / 1000 - */ - hw->ts_gain -= ((s8)val * 37500) / 1000; + hw->ts_gain -= ((s8)val * ts_settings->ts_trim_coeff) / 1000; } return 0; -- 2.51.0