> -----Original Message----- > From: Markus Pargmann [mailto:mpa@xxxxxxxxxxxxxx] > Sent: 17 August, 2015 12:10 > To: Jonathan Cameron > Cc: Tirdea, Irina; Wolfram Sang; linux-iio@xxxxxxxxxxxxxxx; linux-i2c@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Pandruvada, > Srinivas; Peter Meerwald > Subject: Re: [PATCH v5 6/8] iio: gyro: bmg160: optimize i2c transfers in trigger handler > > On Sun, Aug 16, 2015 at 10:24:47AM +0100, Jonathan Cameron wrote: > > On 12/08/15 15:31, Irina Tirdea wrote: > > > Some i2c busses (e.g.: Synopsys DesignWare I2C adapter) need to > > > enable/disable the bus at each i2c transfer and must wait for > > > the enable/disable to happen before sending the data. > > > > > > When reading data in the trigger handler, the bmg160 driver does > > > one i2c transfer for each axis. This has an impact on the frequency > > > of the gyroscope at high sample rates due to additional delays > > > introduced by the i2c bus at each transfer. > > > > > > Reading all axis values in one i2c transfer reduces the delays > > > introduced by the i2c bus. Uses i2c_smbus_read_i2c_block_data_or_emulated > > > that will fallback to reading each axis as a separate word in case i2c > > > block read is not supported. > > > > > > Signed-off-by: Irina Tirdea <irina.tirdea@xxxxxxxxx> > > > Acked-by: Jonathan Cameron <jic23@xxxxxxxxxx> > > > Acked-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx> > > Note, that in the meantime the bmg160 driver just went all regmap > > on us (as part of adding SPI support - though that step hasn't > > happened yet). Hence we'll need a means of telling regmap about this > > possibility. > > Perhaps this is covered by a regmap_bulk_read()? I think it is. However, if that does not work for the i2c controllers I'm testing with I'll take a look at the patches you mention below. I'll rebase this patch on top of your next version for bmg160 and resend. Thanks, Irina > > The series[1] I am working on implements a i2c smbus block data regmap > bus driver. Regmap should then automatically do a block read in > regmap_bulk_read. > > Patch 15 introduces the i2c block data regmap bus driver[2]. > I am only implementing this so I don't break bmc150 behavior. I do not > have the hardware available to test this regmap driver so it would be great > if someone else could test one of the next versions of this bus driver. > > Best regards, > > Markus > > [1] http://thread.gmane.org/gmane.linux.kernel/2018643 > [2] http://thread.gmane.org/gmane.linux.kernel/2018639 > > > > > > --- > > > drivers/iio/gyro/bmg160.c | 18 ++++++++---------- > > > 1 file changed, 8 insertions(+), 10 deletions(-) > > > > > > diff --git a/drivers/iio/gyro/bmg160.c b/drivers/iio/gyro/bmg160.c > > > index b2a6ccb..1ff306d 100644 > > > --- a/drivers/iio/gyro/bmg160.c > > > +++ b/drivers/iio/gyro/bmg160.c > > > @@ -772,6 +772,7 @@ static const struct iio_event_spec bmg160_event = { > > > .sign = 's', \ > > > .realbits = 16, \ > > > .storagebits = 16, \ > > > + .endianness = IIO_LE, \ > > > }, \ > > > .event_spec = &bmg160_event, \ > > > .num_event_specs = 1 \ > > > @@ -809,19 +810,16 @@ static irqreturn_t bmg160_trigger_handler(int irq, void *p) > > > struct iio_poll_func *pf = p; > > > struct iio_dev *indio_dev = pf->indio_dev; > > > struct bmg160_data *data = iio_priv(indio_dev); > > > - int bit, ret, i = 0; > > > + int ret = 0; > > > > > > mutex_lock(&data->mutex); > > > - for (bit = 0; bit < AXIS_MAX; bit++) { > > > - ret = i2c_smbus_read_word_data(data->client, > > > - BMG160_AXIS_TO_REG(bit)); > > > - if (ret < 0) { > > > - mutex_unlock(&data->mutex); > > > - goto err; > > > - } > > > - data->buffer[i++] = ret; > > > - } > > > + ret = i2c_smbus_read_i2c_block_data_or_emulated(data->client, > > > + BMG160_REG_XOUT_L, > > > + AXIS_MAX * 2, > > > + (u8 *)data->buffer); > > > mutex_unlock(&data->mutex); > > > + if (ret < 0) > > > + goto err; > > > > > > iio_push_to_buffers_with_timestamp(indio_dev, data->buffer, > > > pf->timestamp); > > > > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > -- > Pengutronix e.K. | | > Industrial Linux Solutions | http://www.pengutronix.de/ | > Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | > Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | ��.n��������+%������w��{.n�����{��-��)�� jg��� �����ݢj����G���� ���j:+v���w�m������w�������h�����٥
