From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757773AbdCUPyW (ORCPT ); Tue, 21 Mar 2017 11:54:22 -0400 Received: from mail.free-electrons.com ([62.4.15.54]:33721 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756830AbdCUPwy (ORCPT ); Tue, 21 Mar 2017 11:52:54 -0400 From: Quentin Schulz To: jic23@kernel.org, knaack.h@gmx.de, lars@metafoo.de, pmeerw@pmeerw.net Cc: Quentin Schulz , irina.tirdea@intel.com, gregor.boirie@parrot.com, amsfield22@gmail.com, s.trumtrar@pengutronix.de, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, thomas.petazzoni@free-electrons.com Subject: [PATCH] iio: bmg160: reset chip when probing Date: Tue, 21 Mar 2017 16:52:14 +0100 Message-Id: <20170321155214.18060-1-quentin.schulz@free-electrons.com> X-Mailer: git-send-email 2.9.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The gyroscope chip might need to be reset to be used. Without the chip being reset, the driver stopped at the first regmap_read (to get the CHIP_ID) and failed to probe. The datasheet of the gyroscope says that a minimum wait of 30ms after the reset has to be done. This patch has been checked on a BMX055 and the datasheet of the BMG160 and the BMI055 give the same reset register and bits. Signed-off-by: Quentin Schulz --- drivers/iio/gyro/bmg160_core.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/iio/gyro/bmg160_core.c b/drivers/iio/gyro/bmg160_core.c index f7fcfa8..821919d 100644 --- a/drivers/iio/gyro/bmg160_core.c +++ b/drivers/iio/gyro/bmg160_core.c @@ -27,6 +27,7 @@ #include #include #include +#include #include "bmg160.h" #define BMG160_IRQ_NAME "bmg160_event" @@ -52,6 +53,9 @@ #define BMG160_DEF_BW 100 #define BMG160_REG_PMU_BW_RES BIT(7) +#define BMG160_GYRO_REG_RESET 0x14 +#define BMG160_GYRO_RESET_VAL 0xb6 + #define BMG160_REG_INT_MAP_0 0x17 #define BMG160_INT_MAP_0_BIT_ANY BIT(1) @@ -236,6 +240,14 @@ static int bmg160_chip_init(struct bmg160_data *data) int ret; unsigned int val; + /* + * Reset chip to get it in a known good state. A delay of 30ms after + * reset is required according to the datasheet. + */ + regmap_write(data->regmap, BMG160_GYRO_REG_RESET, + BMG160_GYRO_RESET_VAL); + usleep_range(30000, 30700); + ret = regmap_read(data->regmap, BMG160_REG_CHIP_ID, &val); if (ret < 0) { dev_err(dev, "Error reading reg_chip_id\n"); -- 2.9.3