[PATCH 0/2] bmc150-accel driver optimizations

[PATCH 0/2] bmc150-accel driver optimizations

[Irina Tirdea]

Adds optimization of i2c transactions in trigger handler and
usage of available_scan_masks for bmc150-accel.

Irina Tirdea (2):
  iio: accel: bmc150: use available_scan_masks
  iio: accel: bmc150: optimize i2c transfers in trigger handler

 drivers/iio/accel/bmc150-accel.c | 49 +++++++++++++++++++++++++++++++---------
 1 file changed, 38 insertions(+), 11 deletions(-)

-- 
1.9.1

[PATCH 1/2] iio: accel: bmc150: use available_scan_masks

[Irina Tirdea]

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.

This also fixes the issue of accessing the buffer scan_mask
instead of active_scan_mask, since these might not be the
same due to client devices.

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Reviewed-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 f040f40..2eb0102 100644
--- a/drivers/iio/accel/bmc150-accel.c
+++ b/drivers/iio/accel/bmc150-accel.c
@@ -126,6 +126,7 @@ enum bmc150_accel_axis {
 	AXIS_X,
 	AXIS_Y,
 	AXIS_Z,
+	AXIS_MAX,
 };
 
 enum bmc150_power_modes {
@@ -921,6 +922,8 @@ static const struct iio_info bmc150_accel_info = {
 	.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;
@@ -929,8 +932,7 @@ 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->buffer->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) {
@@ -1178,6 +1180,7 @@ 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

[PATCH 2/2] iio: accel: bmc150: optimize i2c transfers in trigger handler

[Irina Tirdea]

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. In case i2c block read is not supported,
fallback to reading each axis as a separate word.

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Reviewed-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
---
 drivers/iio/accel/bmc150-accel.c | 44 +++++++++++++++++++++++++++++++---------
 1 file changed, 34 insertions(+), 10 deletions(-)

diff --git a/drivers/iio/accel/bmc150-accel.c b/drivers/iio/accel/bmc150-accel.c
index 2eb0102..db2e362 100644
--- a/drivers/iio/accel/bmc150-accel.c
+++ b/drivers/iio/accel/bmc150-accel.c
@@ -163,6 +163,8 @@ struct bmc150_accel_data {
 	bool motion_trigger_on;
 	int64_t timestamp;
 	const struct bmc150_accel_chip_info *chip_info;
+	s32 (*read_block_data)(const struct i2c_client *client, u8 command,
+			       u8 length, u8 *values);
 };
 
 static const struct {
@@ -206,6 +208,22 @@ static const struct {
 				       {500000, BMC150_ACCEL_SLEEP_500_MS},
 				       {1000000, BMC150_ACCEL_SLEEP_1_SEC} };
 
+static s32 bmc150_accel_read_block_data(const struct i2c_client *client,
+					u8 command, u8 length, u8 *values)
+{
+	s32 data;
+	u8 i;
+
+	for (i = 0; i < length; i += 2) {
+		data = i2c_smbus_read_word_data(client, command + i);
+		if (data < 0)
+			return data;
+
+		values[i] = data & 0xFF;
+		values[i+1] = data >> 8;
+	}
+	return i;
+}
 
 static int bmc150_accel_set_mode(struct bmc150_accel_data *data,
 				 enum bmc150_power_modes mode,
@@ -929,19 +947,14 @@ 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 = data->read_block_data(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,
 					   data->timestamp);
@@ -1153,6 +1166,11 @@ static int bmc150_accel_probe(struct i2c_client *client,
 	const char *name = NULL;
 	int chip_id = 0;
 
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_BYTE_DATA |
+				     I2C_FUNC_SMBUS_READ_WORD_DATA))
+		return -ENODEV;
+
 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 	if (!indio_dev)
 		return -ENOMEM;
@@ -1161,6 +1179,12 @@ static int bmc150_accel_probe(struct i2c_client *client,
 	i2c_set_clientdata(client, indio_dev);
 	data->client = client;
 
+	if (i2c_check_functionality(client->adapter,
+				    I2C_FUNC_SMBUS_READ_I2C_BLOCK))
+		data->read_block_data = i2c_smbus_read_i2c_block_data;
+	else
+		data->read_block_data = bmc150_accel_read_block_data;
+
 	if (id) {
 		name = id->name;
 		chip_id = id->driver_data;
-- 
1.9.1

Re: [PATCH 0/2] bmc150-accel driver optimizations

[Peter Meerwald]

> Adds optimization of i2c transactions in trigger handler and
> usage of available_scan_masks for bmc150-accel.

same comments as for kxcjk-1013, this changes the capabilities of the 
driver
 
> Irina Tirdea (2):
>   iio: accel: bmc150: use available_scan_masks
>   iio: accel: bmc150: optimize i2c transfers in trigger handler
> 
>  drivers/iio/accel/bmc150-accel.c | 49 +++++++++++++++++++++++++++++++---------
>  1 file changed, 38 insertions(+), 11 deletions(-)
> 
> 

-- 

Peter Meerwald
+43-664-2444418 (mobile)

RE: [PATCH 0/2] bmc150-accel driver optimizations

[Tirdea, Irina]

> -----Original Message-----
> From: linux-iio-owner@vger.kernel.org [mailto:linux-iio-owner@vger.kernel.org] On Behalf Of Peter Meerwald
> Sent: 16 February, 2015 21:27
> To: Tirdea, Irina
> Cc: Jonathan Cameron; linux-iio@vger.kernel.org; linux-kernel@vger.kernel.org; Pandruvada, Srinivas; Reus, Adriana
> Subject: Re: [PATCH 0/2] bmc150-accel driver optimizations
> 
> 
> > Adds optimization of i2c transactions in trigger handler and
> > usage of available_scan_masks for bmc150-accel.
> 
> same comments as for kxcjk-1013, this changes the capabilities of the
> driver
> 
Will fix the comments for all the patchsets.

Thanks,
Irina

> > Irina Tirdea (2):
> >   iio: accel: bmc150: use available_scan_masks
> >   iio: accel: bmc150: optimize i2c transfers in trigger handler
> >
> >  drivers/iio/accel/bmc150-accel.c | 49 +++++++++++++++++++++++++++++++---------
> >  1 file changed, 38 insertions(+), 11 deletions(-)
> >
> >
> 
> --
> 
> Peter Meerwald
> +43-664-2444418 (mobile)
> --
> 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

RE: [PATCH 0/2] bmc150-accel driver optimizations

[Tirdea, Irina]

> -----Original Message-----
> From: linux-iio-owner@vger.kernel.org [mailto:linux-iio-owner@vger.kernel=
.org] On Behalf Of Peter Meerwald
> Sent: 16 February, 2015 21:27
> To: Tirdea, Irina
> Cc: Jonathan Cameron; linux-iio@vger.kernel.org; linux-kernel@vger.kernel=
.org; Pandruvada, Srinivas; Reus, Adriana
> Subject: Re: [PATCH 0/2] bmc150-accel driver optimizations
>=20
>=20
> > Adds optimization of i2c transactions in trigger handler and
> > usage of available_scan_masks for bmc150-accel.
>=20
> same comments as for kxcjk-1013, this changes the capabilities of the
> driver
>=20
Will fix the comments for all the patchsets.

Thanks,
Irina

> > Irina Tirdea (2):
> >   iio: accel: bmc150: use available_scan_masks
> >   iio: accel: bmc150: optimize i2c transfers in trigger handler
> >
> >  drivers/iio/accel/bmc150-accel.c | 49 +++++++++++++++++++++++++++++++-=
--------
> >  1 file changed, 38 insertions(+), 11 deletions(-)
> >
> >
>=20
> --
>=20
> Peter Meerwald
> +43-664-2444418 (mobile)
> --
> 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

Re: [PATCH 0/2] bmc150-accel driver optimizations

[Jonathan Cameron]

On 20/02/15 12:05, Tirdea, Irina wrote:
> 
> 
>> -----Original Message-----
>> From: linux-iio-owner@vger.kernel.org [mailto:linux-iio-owner@vger.kernel.org] On Behalf Of Peter Meerwald
>> Sent: 16 February, 2015 21:27
>> To: Tirdea, Irina
>> Cc: Jonathan Cameron; linux-iio@vger.kernel.org; linux-kernel@vger.kernel.org; Pandruvada, Srinivas; Reus, Adriana
>> Subject: Re: [PATCH 0/2] bmc150-accel driver optimizations
>>
>>
>>> Adds optimization of i2c transactions in trigger handler and
>>> usage of available_scan_masks for bmc150-accel.
>>
>> same comments as for kxcjk-1013, this changes the capabilities of the
>> driver
>>
> Will fix the comments for all the patchsets.
> 
> Thanks,
> Irina
Same point as you made in the other driver applies here and this is fine
as the core will deal with it.

Anyhow, I'm happy with this, except for the excellent idea of putting
the emulation code into the i2c core.  No particular rush at the moment
given where we are in the cycle so might as well wait for that to pan out.

Jonathan
> 
>>> Irina Tirdea (2):
>>>   iio: accel: bmc150: use available_scan_masks
>>>   iio: accel: bmc150: optimize i2c transfers in trigger handler
>>>
>>>  drivers/iio/accel/bmc150-accel.c | 49 +++++++++++++++++++++++++++++++---------
>>>  1 file changed, 38 insertions(+), 11 deletions(-)
>>>
>>>
>>
>> --
>>
>> Peter Meerwald
>> +43-664-2444418 (mobile)
>> --
>> 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