From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from saturn.retrosnub.co.uk ([178.18.118.26]:38222 "EHLO saturn.retrosnub.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932386AbaHGOVZ (ORCPT ); Thu, 7 Aug 2014 10:21:25 -0400 Message-ID: <53E38B62.8010208@kernel.org> Date: Thu, 07 Aug 2014 15:21:22 +0100 From: Jonathan Cameron MIME-Version: 1.0 To: Martin Fuzzey , linux-iio@vger.kernel.org CC: pmeerw@pmeerw.net Subject: Re: [PATCH V2 1/8] iio: mma8452: Initialise before activating References: <20140729090128.4618.92936.stgit@localhost> <20140729090131.4618.11083.stgit@localhost> In-Reply-To: <20140729090131.4618.11083.stgit@localhost> Content-Type: text/plain; charset=utf-8 Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org On 29/07/14 10:01, Martin Fuzzey wrote: > Many of the hardware configuration registers may only be modified while the > device is inactive. > > Currently the probe code first activates the device and then modifies the > registers (eg to set the scale). This doesn't actually work but is not > noticed since the scale used is the default value. > > While at it also issue a hardware reset command at probe time. > > Signed-off-by: Martin Fuzzey Looks fine to me but I'd like an OK from Peter for this series. J > --- > drivers/iio/accel/mma8452.c | 39 ++++++++++++++++++++++++++++++++++----- > 1 file changed, 34 insertions(+), 5 deletions(-) > > diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c > index 3c12d49..04a4f34 100644 > --- a/drivers/iio/accel/mma8452.c > +++ b/drivers/iio/accel/mma8452.c > @@ -32,6 +32,7 @@ > #define MMA8452_OFF_Z 0x31 > #define MMA8452_CTRL_REG1 0x2a > #define MMA8452_CTRL_REG2 0x2b > +#define MMA8452_CTRL_REG2_RST BIT(6) > > #define MMA8452_STATUS_DRDY (BIT(2) | BIT(1) | BIT(0)) > > @@ -111,7 +112,7 @@ static const int mma8452_samp_freq[8][2] = { > {6, 250000}, {1, 560000} > }; > > -/* > +/* This ought to be in a separate cleanup patch. Just adds noise to the important stuff in here! Not important though so don't bother rerolling the series for this. > * Hardware has fullscale of -2G, -4G, -8G corresponding to raw value -2048 > * The userspace interface uses m/s^2 and we declare micro units > * So scale factor is given by: > @@ -335,6 +336,30 @@ static const struct iio_info mma8452_info = { > > static const unsigned long mma8452_scan_masks[] = {0x7, 0}; > > +static int mma8452_reset(struct i2c_client *client) > +{ > + int i; > + int ret; > + > + ret = i2c_smbus_write_byte_data(client, MMA8452_CTRL_REG2, > + MMA8452_CTRL_REG2_RST); > + if (ret) > + return ret; > + > + for (i = 0; i < 10; i++) { > + udelay(100); > + ret = i2c_smbus_read_byte_data(client, MMA8452_CTRL_REG2); > + if (ret == -EIO) > + continue; /* I2C comm reset */ > + if (ret < 0) > + return ret; > + if (!(ret & MMA8452_CTRL_REG2_RST)) > + return 0; > + } > + > + return -ETIMEDOUT; > +} > + > static int mma8452_probe(struct i2c_client *client, > const struct i2c_device_id *id) > { > @@ -365,10 +390,7 @@ static int mma8452_probe(struct i2c_client *client, > indio_dev->num_channels = ARRAY_SIZE(mma8452_channels); > indio_dev->available_scan_masks = mma8452_scan_masks; > > - data->ctrl_reg1 = MMA8452_CTRL_ACTIVE | > - (MMA8452_CTRL_DR_DEFAULT << MMA8452_CTRL_DR_SHIFT); > - ret = i2c_smbus_write_byte_data(client, MMA8452_CTRL_REG1, > - data->ctrl_reg1); > + ret = mma8452_reset(client); > if (ret < 0) > return ret; > > @@ -378,6 +400,13 @@ static int mma8452_probe(struct i2c_client *client, > if (ret < 0) > return ret; > > + data->ctrl_reg1 = MMA8452_CTRL_ACTIVE | > + (MMA8452_CTRL_DR_DEFAULT << MMA8452_CTRL_DR_SHIFT); > + ret = i2c_smbus_write_byte_data(client, MMA8452_CTRL_REG1, > + data->ctrl_reg1); > + if (ret < 0) > + return ret; > + > ret = iio_triggered_buffer_setup(indio_dev, NULL, > mma8452_trigger_handler, NULL); > if (ret < 0) > > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >