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Groups > linux.kernel > #1206166 > unrolled thread

[PATCH v5 0/8] Add support for best effort block read emulation

Started byIrina Tirdea <irina.tirdea@intel.com>
First post2015-08-12 16:40 +0200
Last post2015-08-12 16:40 +0200
Articles 8 — 4 participants

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  [PATCH v5 0/8] Add support for best effort block read emulation Irina Tirdea <irina.tirdea@intel.com> - 2015-08-12 16:40 +0200
    [PATCH v5 4/8] iio: accel: bmc150: optimize i2c transfers in trigger handler Irina Tirdea <irina.tirdea@intel.com> - 2015-08-12 16:40 +0200
    [PATCH v5 6/8] iio: gyro: bmg160: optimize i2c transfers in trigger handler Irina Tirdea <irina.tirdea@intel.com> - 2015-08-12 16:40 +0200
      Re: [PATCH v5 6/8] iio: gyro: bmg160: optimize i2c transfers in  trigger handler Jonathan Cameron <jic23@kernel.org> - 2015-08-16 11:30 +0200
        Re: [PATCH v5 6/8] iio: gyro: bmg160: optimize i2c transfers in  trigger handler Markus Pargmann <mpa@pengutronix.de> - 2015-08-17 11:10 +0200
          RE: [PATCH v5 6/8] iio: gyro: bmg160: optimize i2c transfers in  trigger handler "Tirdea, Irina" <irina.tirdea@intel.com> - 2015-08-17 11:50 +0200
        RE: [PATCH v5 6/8] iio: gyro: bmg160: optimize i2c transfers in  trigger handler "Tirdea, Irina" <irina.tirdea@intel.com> - 2015-08-17 11:40 +0200
    [PATCH v5 3/8] iio: accel: bmc150: use available_scan_masks Irina Tirdea <irina.tirdea@intel.com> - 2015-08-12 16:40 +0200

#1206166 — [PATCH v5 0/8] Add support for best effort block read emulation

FromIrina Tirdea <irina.tirdea@intel.com>
Date2015-08-12 16:40 +0200
Subject[PATCH v5 0/8] Add support for best effort block read emulation
Message-ID<pWFm9-7bv-7@gated-at.bofh.it>
This is version 5 for adding i2c_smbus_read_i2c_block_data_or_emulated
to i2c-core.

Jonathan, I did not add your Reviewed-by to the patch adding the 
i2c_smbus_read_i2c_block_data_or_emulated function since I made some
changes to the code.

Thanks,
Irina

Changes from v4:
 - optimized the code for i2c_smbus_read_i2c_block_data_or_emulated as
Wolfram suggested
 - dropped the error message from i2c_smbus_read_i2c_block_data_or_emulated
 - fixed documentation to specify I2C_SMBUS_BLOCK_MAX instead of 32

Changes from v3:
 - when reading an odd number of bytes using word emulation, read an even
number of bytes using word reads and the last byte using byte read
 - code styling changes to improve readability
 - add a comment about addressing assumptions to the
i2c_smbus_read_i2c_block_data_or_emulated function as Jonathan suggested
 - add Acked-by from Jonathan and Srinivas to the iio changes

Changes from v2:
 - changed bmc150-accel, kxcjk-1013 and bmg160 drivers to use
i2c_smbus_read_i2c_block_data_or_emulated

Changes from v1:
 - dropped the RFC tag
 - changed at24 to use i2c_smbus_read_i2c_block_data_or_emulated
 - when reading an odd number of bytes using word emulation, read an even
number of bytes and drop the last one
 - add a comment that this might not be suitable for all I2C slaves

Adriana Reus (2):
  iio: accel: kxcjk-1013: use available_scan_masks
  iio: accel: kxcjk-1013: optimize i2c transfers in trigger handler

Irina Tirdea (6):
  i2c: core: Add support for best effort block read emulation
  eeprom: at24: use i2c_smbus_read_i2c_block_data_or_emulated
  iio: accel: bmc150: use available_scan_masks
  iio: accel: bmc150: optimize i2c transfers in trigger handler
  iio: gyro: bmg160: use available_scan_masks
  iio: gyro: bmg160: optimize i2c transfers in trigger handler

 drivers/i2c/i2c-core.c           | 57 ++++++++++++++++++++++++++++++++++++++++
 drivers/iio/accel/bmc150-accel.c | 23 ++++++++--------
 drivers/iio/accel/kxcjk-1013.c   | 24 ++++++++---------
 drivers/iio/gyro/bmg160.c        | 23 ++++++++--------
 drivers/misc/eeprom/at24.c       | 37 +++++---------------------
 include/linux/i2c.h              |  3 +++
 6 files changed, 102 insertions(+), 65 deletions(-)

-- 
1.9.1

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#1206168 — [PATCH v5 4/8] iio: accel: bmc150: optimize i2c transfers in trigger handler

FromIrina Tirdea <irina.tirdea@intel.com>
Date2015-08-12 16:40 +0200
Subject[PATCH v5 4/8] iio: accel: bmc150: optimize i2c transfers in trigger handler
Message-ID<pWFma-7bv-13@gated-at.bofh.it>
In reply to#1206166
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 bmc150 accel driver does
one i2c transfer for each axis. This has an impact on the frequency
of the accelerometer 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@intel.com>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
---
 drivers/iio/accel/bmc150-accel.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/drivers/iio/accel/bmc150-accel.c b/drivers/iio/accel/bmc150-accel.c
index 40da2d0..a38e3f4 100644
--- a/drivers/iio/accel/bmc150-accel.c
+++ b/drivers/iio/accel/bmc150-accel.c
@@ -1082,6 +1082,7 @@ static const struct iio_event_spec bmc150_accel_event = {
 		.realbits = (bits),					\
 		.storagebits = 16,					\
 		.shift = 16 - (bits),					\
+		.endianness = IIO_LE,					\
 	},								\
 	.event_spec = &bmc150_accel_event,				\
 	.num_event_specs = 1						\
@@ -1208,19 +1209,16 @@ static irqreturn_t bmc150_accel_trigger_handler(int irq, void *p)
 	struct iio_poll_func *pf = p;
 	struct iio_dev *indio_dev = pf->indio_dev;
 	struct bmc150_accel_data *data = iio_priv(indio_dev);
-	int bit, ret, i = 0;
+	int ret;
 
 	mutex_lock(&data->mutex);
-	for (bit = 0; bit < AXIS_MAX; bit++) {
-		ret = i2c_smbus_read_word_data(data->client,
-					       BMC150_ACCEL_AXIS_TO_REG(bit));
-		if (ret < 0) {
-			mutex_unlock(&data->mutex);
-			goto err_read;
-		}
-		data->buffer[i++] = ret;
-	}
+	ret = i2c_smbus_read_i2c_block_data_or_emulated(data->client,
+							BMC150_ACCEL_REG_XOUT_L,
+							AXIS_MAX * 2,
+							(u8 *)data->buffer);
 	mutex_unlock(&data->mutex);
+	if (ret < 0)
+		goto err_read;
 
 	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
 					   pf->timestamp);
-- 
1.9.1

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#1206169 — [PATCH v5 6/8] iio: gyro: bmg160: optimize i2c transfers in trigger handler

FromIrina Tirdea <irina.tirdea@intel.com>
Date2015-08-12 16:40 +0200
Subject[PATCH v5 6/8] iio: gyro: bmg160: optimize i2c transfers in trigger handler
Message-ID<pWFmb-7bv-55@gated-at.bofh.it>
In reply to#1206166
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@intel.com>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
---
 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);
-- 
1.9.1

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#1208222 — Re: [PATCH v5 6/8] iio: gyro: bmg160: optimize i2c transfers in trigger handler

FromJonathan Cameron <jic23@kernel.org>
Date2015-08-16 11:30 +0200
SubjectRe: [PATCH v5 6/8] iio: gyro: bmg160: optimize i2c transfers in trigger handler
Message-ID<pY2qn-4ld-25@gated-at.bofh.it>
In reply to#1206169
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@intel.com>
> Acked-by: Jonathan Cameron <jic23@kernel.org>
> Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
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.

> ---
>  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);
> 

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#1208486 — Re: [PATCH v5 6/8] iio: gyro: bmg160: optimize i2c transfers in trigger handler

FromMarkus Pargmann <mpa@pengutronix.de>
Date2015-08-17 11:10 +0200
SubjectRe: [PATCH v5 6/8] iio: gyro: bmg160: optimize i2c transfers in trigger handler
Message-ID<pYoAz-2Ok-15@gated-at.bofh.it>
In reply to#1208222

[Multipart message — attachments visible in raw view] — view raw

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@intel.com>
> > Acked-by: Jonathan Cameron <jic23@kernel.org>
> > Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
> 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()?

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);
> > 
> 
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#1208505 — RE: [PATCH v5 6/8] iio: gyro: bmg160: optimize i2c transfers in trigger handler

From"Tirdea, Irina" <irina.tirdea@intel.com>
Date2015-08-17 11:50 +0200
SubjectRE: [PATCH v5 6/8] iio: gyro: bmg160: optimize i2c transfers in trigger handler
Message-ID<pYpdf-3yi-19@gated-at.bofh.it>
In reply to#1208486
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#1208499 — RE: [PATCH v5 6/8] iio: gyro: bmg160: optimize i2c transfers in trigger handler

From"Tirdea, Irina" <irina.tirdea@intel.com>
Date2015-08-17 11:40 +0200
SubjectRE: [PATCH v5 6/8] iio: gyro: bmg160: optimize i2c transfers in trigger handler
Message-ID<pYp3A-3mN-17@gated-at.bofh.it>
In reply to#1208222

> -----Original Message-----
> From: Jonathan Cameron [mailto:jic23@kernel.org]
> Sent: 16 August, 2015 12:25
> To: Tirdea, Irina; Wolfram Sang; linux-iio@vger.kernel.org; linux-i2c@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org; Pandruvada, Srinivas; Peter Meerwald
> Subject: Re: [PATCH v5 6/8] iio: gyro: bmg160: optimize i2c transfers in trigger handler
> 
> 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@intel.com>
> > Acked-by: Jonathan Cameron <jic23@kernel.org>
> > Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
> 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.

I think regmap_bulk_read might be enough in my case, but I'll have to
test this. I have also seen there are similar changes for the bmc150 driver,
so I will rebase my changes on top of the regmap ones. That leaves only the
kxcjk-1013 changes to be applied from this patchset.

Thanks,
Irina

> 
> > ---
> >  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);
> >

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#1206170 — [PATCH v5 3/8] iio: accel: bmc150: use available_scan_masks

FromIrina Tirdea <irina.tirdea@intel.com>
Date2015-08-12 16:40 +0200
Subject[PATCH v5 3/8] iio: accel: bmc150: use available_scan_masks
Message-ID<pWFma-7bv-15@gated-at.bofh.it>
In reply to#1206166
Use available_scan_masks to allow the iio core to select
the data to send to userspace depending on which axes are
enabled, instead of doing this in the driver's interrupt
handler.

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
---
 drivers/iio/accel/bmc150-accel.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/accel/bmc150-accel.c b/drivers/iio/accel/bmc150-accel.c
index cc5a357..40da2d0 100644
--- a/drivers/iio/accel/bmc150-accel.c
+++ b/drivers/iio/accel/bmc150-accel.c
@@ -136,6 +136,7 @@ enum bmc150_accel_axis {
 	AXIS_X,
 	AXIS_Y,
 	AXIS_Z,
+	AXIS_MAX,
 };
 
 enum bmc150_power_modes {
@@ -1200,6 +1201,8 @@ static const struct iio_info bmc150_accel_info_fifo = {
 	.driver_module		= THIS_MODULE,
 };
 
+static const unsigned long bmc150_accel_scan_masks[] = {0x7, 0};
+
 static irqreturn_t bmc150_accel_trigger_handler(int irq, void *p)
 {
 	struct iio_poll_func *pf = p;
@@ -1208,8 +1211,7 @@ static irqreturn_t bmc150_accel_trigger_handler(int irq, void *p)
 	int bit, ret, i = 0;
 
 	mutex_lock(&data->mutex);
-	for_each_set_bit(bit, indio_dev->active_scan_mask,
-			 indio_dev->masklength) {
+	for (bit = 0; bit < AXIS_MAX; bit++) {
 		ret = i2c_smbus_read_word_data(data->client,
 					       BMC150_ACCEL_AXIS_TO_REG(bit));
 		if (ret < 0) {
@@ -1647,6 +1649,7 @@ static int bmc150_accel_probe(struct i2c_client *client,
 	indio_dev->dev.parent = &client->dev;
 	indio_dev->channels = data->chip_info->channels;
 	indio_dev->num_channels = data->chip_info->num_channels;
+	indio_dev->available_scan_masks = bmc150_accel_scan_masks;
 	indio_dev->name = name;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->info = &bmc150_accel_info;
-- 
1.9.1

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