[PATCH 0/3] iio: accel: bmc150: DMA-safe buffers and use iio_push_to_buffers_with_ts()

[PATCH 0/3] iio: accel: bmc150: DMA-safe buffers and use iio_push_to_buffers_with_ts()

[Yash Suthar]

The trigger path used a plain s16 buffer while the FIFO path already had
a properly typed scan member (__le16 + aligned timestamp). Those two
buffers did the same job, and s16 does not represent little-endian data.
Drop the duplicate, keep scan at the end of struct bmc150_accel_data with
IIO_DMA_MINALIGN, and use it for both the trigger and FIFO paths.

The FIFO and read_raw buffers are passed to regmap bulk/raw reads, which
is not DMA-safe. Move them into struct bmc150_accel_data after scan and
aligned to IIO_DMA_MINALIGN.

Finally, replace the deprecated iio_push_to_buffers_with_timestamp() with
iio_push_to_buffers_with_ts() so the push sites pass an explicit buffer
size.

This supersedes the earlier standalone patches:
Link: https://lore.kernel.org/linux-iio/20260808220236.421832-1-yashsuthar983@gmail.com/
Link: https://lore.kernel.org/linux-iio/20260809111303.496393-1-yashsuthar983@gmail.com/

Yash Suthar (3):
  iio: accel: bmc150: use aligned scan buffer for both trigger and fifo
  iio: accel: bmc150: use DMA-safe buffers for regmap bulk reads
  iio: accel: bmc150: use iio_push_to_buffers_with_ts()

 drivers/iio/accel/bmc150-accel-core.c | 28 ++++++++++++---------------
 drivers/iio/accel/bmc150-accel.h      | 20 ++++++++++---------
 2 files changed, 23 insertions(+), 25 deletions(-)

-- 
2.43.0

[PATCH 1/3] iio: accel: bmc150: use aligned scan buffer for both trigger and fifo

[Yash Suthar]

Drop buffer as duplicate and s16 is not correct we needed __le16 as little
endian, keep scan at the end of the bmc150_accel_data struct with
IIO_DMA_MINALIGN, and use it for both paths.

Fixes: bd7fe5b71918 ("iio: accel: BMC150 accel support")
Suggested-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Yash Suthar <yashsuthar983@gmail.com>
---
 drivers/iio/accel/bmc150-accel-core.c | 10 ++++------
 drivers/iio/accel/bmc150-accel.h      | 14 +++++---------
 2 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/drivers/iio/accel/bmc150-accel-core.c b/drivers/iio/accel/bmc150-accel-core.c
index dc8a6285cf3d..596ff8267ead 100644
--- a/drivers/iio/accel/bmc150-accel-core.c
+++ b/drivers/iio/accel/bmc150-accel-core.c
@@ -1191,14 +1191,12 @@ static irqreturn_t bmc150_accel_trigger_handler(int irq, void *p)
 
 	mutex_lock(&data->mutex);
 	ret = regmap_bulk_read(data->regmap, BMC150_ACCEL_REG_XOUT_L,
-			       data->buffer, AXIS_MAX * 2);
+			       data->scan.channels, AXIS_MAX * 2);
+	if (!ret)
+		iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
+						   pf->timestamp);
 	mutex_unlock(&data->mutex);
-	if (ret < 0)
-		goto err_read;
 
-	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
-					   pf->timestamp);
-err_read:
 	iio_trigger_notify_done(indio_dev->trig);
 
 	return IRQ_HANDLED;
diff --git a/drivers/iio/accel/bmc150-accel.h b/drivers/iio/accel/bmc150-accel.h
index e8f26198359f..9deff256aed5 100644
--- a/drivers/iio/accel/bmc150-accel.h
+++ b/drivers/iio/accel/bmc150-accel.h
@@ -64,15 +64,6 @@ struct bmc150_accel_data {
 	struct bmc150_accel_trigger triggers[BMC150_ACCEL_TRIGGERS];
 	struct mutex mutex;
 	u8 fifo_mode, watermark;
-	s16 buffer[8];
-	/*
-	 * Ensure there is sufficient space and correct alignment for
-	 * the timestamp if enabled
-	 */
-	struct {
-		__le16 channels[3];
-		aligned_s64 ts;
-	} scan;
 	u8 bw_bits;
 	u32 slope_dur;
 	u32 slope_thres;
@@ -85,6 +76,11 @@ struct bmc150_accel_data {
 	void (*resume_callback)(struct device *dev);
 	struct delayed_work resume_work;
 	struct iio_mount_matrix orientation;
+	/* Ensure correct alignment of timestamp and DMA safety */
+	struct {
+		__le16 channels[3];
+		aligned_s64 ts;
+	} scan __aligned(IIO_DMA_MINALIGN);
 };
 
 int bmc150_accel_core_probe(struct device *dev, struct regmap *regmap, int irq,
-- 
2.43.0

Re: [PATCH 1/3] iio: accel: bmc150: use aligned scan buffer for both trigger and fifo

[Linus Walleij]

On Fri, Aug 14, 2026 at 12:19 PM Yash Suthar <yashsuthar983@gmail.com> wrote:

> Drop buffer as duplicate and s16 is not correct we needed __le16 as little
> endian, keep scan at the end of the bmc150_accel_data struct with
> IIO_DMA_MINALIGN, and use it for both paths.
>
> Fixes: bd7fe5b71918 ("iio: accel: BMC150 accel support")
> Suggested-by: Jonathan Cameron <jic23@kernel.org>
> Signed-off-by: Yash Suthar <yashsuthar983@gmail.com>

This is indeed a better way to achieve alignment.
Reviewed-by: Linus Walleij <linusw@kernel.org>

Yours,
Linus Walleij

[PATCH 2/3] iio: accel: bmc150: use DMA-safe buffers for regmap bulk reads

[Yash Suthar]

The FIFO and read_raw buffers are passed to regmap bulk/raw reads
,which is not DMA-safe.Moved them into struct bmc150_accel_data
after scan, each aligned to IIO_DMA_MINALIGN.

Suggested-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Yash Suthar <yashsuthar983@gmail.com>
---
 drivers/iio/accel/bmc150-accel-core.c | 14 ++++++--------
 drivers/iio/accel/bmc150-accel.h      |  6 ++++++
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/iio/accel/bmc150-accel-core.c b/drivers/iio/accel/bmc150-accel-core.c
index 596ff8267ead..30d91d417ac4 100644
--- a/drivers/iio/accel/bmc150-accel-core.c
+++ b/drivers/iio/accel/bmc150-accel-core.c
@@ -125,7 +125,6 @@
 #define BMC150_ACCEL_REG_FIFO_CONFIG0		0x30
 #define BMC150_ACCEL_REG_FIFO_CONFIG1		0x3E
 #define BMC150_ACCEL_REG_FIFO_DATA		0x3F
-#define BMC150_ACCEL_FIFO_LENGTH		32
 
 enum bmc150_accel_axis {
 	AXIS_X,
@@ -622,7 +621,6 @@ static int bmc150_accel_get_axis(struct bmc150_accel_data *data,
 	struct device *dev = regmap_get_device(data->regmap);
 	int ret;
 	int axis = chan->scan_index;
-	__le16 raw_val;
 
 	mutex_lock(&data->mutex);
 	ret = bmc150_accel_set_power_state(data, true);
@@ -632,14 +630,14 @@ static int bmc150_accel_get_axis(struct bmc150_accel_data *data,
 	}
 
 	ret = regmap_bulk_read(data->regmap, BMC150_ACCEL_AXIS_TO_REG(axis),
-			       &raw_val, sizeof(raw_val));
+			       &data->regval, sizeof(data->regval));
 	if (ret < 0) {
 		dev_err(dev, "Error reading axis %d\n", axis);
 		bmc150_accel_set_power_state(data, false);
 		mutex_unlock(&data->mutex);
 		return ret;
 	}
-	*val = sign_extend32(le16_to_cpu(raw_val) >> chan->scan_type.shift,
+	*val = sign_extend32(le16_to_cpu(data->regval) >> chan->scan_type.shift,
 			     chan->scan_type.realbits - 1);
 	ret = bmc150_accel_set_power_state(data, false);
 	mutex_unlock(&data->mutex);
@@ -918,7 +916,7 @@ static int bmc150_accel_set_watermark(struct iio_dev *indio_dev, unsigned val)
  * frame data is discarded.
  */
 static int bmc150_accel_fifo_transfer(struct bmc150_accel_data *data,
-				      char *buffer, int samples)
+				      void *buffer, int samples)
 {
 	struct device *dev = regmap_get_device(data->regmap);
 	int sample_length = 3 * 2;
@@ -941,7 +939,6 @@ static int __bmc150_accel_fifo_flush(struct iio_dev *indio_dev,
 	struct device *dev = regmap_get_device(data->regmap);
 	int ret, i;
 	u8 count;
-	u16 buffer[BMC150_ACCEL_FIFO_LENGTH * 3];
 	int64_t tstamp;
 	uint64_t sample_period;
 	unsigned int val;
@@ -993,7 +990,7 @@ static int __bmc150_accel_fifo_flush(struct iio_dev *indio_dev,
 
 	count = min_t(u8, count, BMC150_ACCEL_FIFO_LENGTH);
 
-	ret = bmc150_accel_fifo_transfer(data, (u8 *)buffer, count);
+	ret = bmc150_accel_fifo_transfer(data, data->fifo_buff, count);
 	if (ret)
 		return ret;
 
@@ -1008,7 +1005,8 @@ static int __bmc150_accel_fifo_flush(struct iio_dev *indio_dev,
 
 		j = 0;
 		iio_for_each_active_channel(indio_dev, bit)
-			memcpy(&data->scan.channels[j++], &buffer[i * 3 + bit],
+			memcpy(&data->scan.channels[j++],
+			       &data->fifo_buff[i * 3 + bit],
 			       sizeof(data->scan.channels[0]));
 
 		iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
diff --git a/drivers/iio/accel/bmc150-accel.h b/drivers/iio/accel/bmc150-accel.h
index 9deff256aed5..a1734f5d30a4 100644
--- a/drivers/iio/accel/bmc150-accel.h
+++ b/drivers/iio/accel/bmc150-accel.h
@@ -56,6 +56,8 @@ enum bmc150_accel_trigger_id {
 	BMC150_ACCEL_TRIGGERS,
 };
 
+#define BMC150_ACCEL_FIFO_LENGTH		32
+
 struct bmc150_accel_data {
 	struct regmap *regmap;
 	int irq;
@@ -81,6 +83,10 @@ struct bmc150_accel_data {
 		__le16 channels[3];
 		aligned_s64 ts;
 	} scan __aligned(IIO_DMA_MINALIGN);
+	/* DMA-safe buffers for bulk/raw reads */
+	__le16 fifo_buff[BMC150_ACCEL_FIFO_LENGTH * 3]
+		__aligned(IIO_DMA_MINALIGN);
+	__le16 regval __aligned(IIO_DMA_MINALIGN);
 };
 
 int bmc150_accel_core_probe(struct device *dev, struct regmap *regmap, int irq,
-- 
2.43.0

Re: [PATCH 2/3] iio: accel: bmc150: use DMA-safe buffers for regmap bulk reads

[Linus Walleij]

On Fri, Aug 14, 2026 at 12:19 PM Yash Suthar <yashsuthar983@gmail.com> wrote:

> The FIFO and read_raw buffers are passed to regmap bulk/raw reads
> ,which is not DMA-safe.Moved them into struct bmc150_accel_data
> after scan, each aligned to IIO_DMA_MINALIGN.
>
> Suggested-by: Jonathan Cameron <jic23@kernel.org>
> Signed-off-by: Yash Suthar <yashsuthar983@gmail.com>

Reviewed-by: Linus Walleij <linusw@kernel.org>

Yours,
Linus Walleij

[PATCH 3/3] iio: accel: bmc150: use iio_push_to_buffers_with_ts()

[Yash Suthar]

Replace deprecated iio_push_to_buffers_with_timestamp() with
iio_push_to_buffers_with_ts() to allow source size runtime checks.

Suggested-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Yash Suthar <yashsuthar983@gmail.com>
---
 drivers/iio/accel/bmc150-accel-core.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/accel/bmc150-accel-core.c b/drivers/iio/accel/bmc150-accel-core.c
index 30d91d417ac4..476c020c41f0 100644
--- a/drivers/iio/accel/bmc150-accel-core.c
+++ b/drivers/iio/accel/bmc150-accel-core.c
@@ -1009,8 +1009,8 @@ static int __bmc150_accel_fifo_flush(struct iio_dev *indio_dev,
 			       &data->fifo_buff[i * 3 + bit],
 			       sizeof(data->scan.channels[0]));
 
-		iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
-						   tstamp);
+		iio_push_to_buffers_with_ts(indio_dev, &data->scan,
+					    sizeof(data->scan), tstamp);
 
 		tstamp += sample_period;
 	}
@@ -1191,8 +1191,8 @@ static irqreturn_t bmc150_accel_trigger_handler(int irq, void *p)
 	ret = regmap_bulk_read(data->regmap, BMC150_ACCEL_REG_XOUT_L,
 			       data->scan.channels, AXIS_MAX * 2);
 	if (!ret)
-		iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
-						   pf->timestamp);
+		iio_push_to_buffers_with_ts(indio_dev, &data->scan,
+					    sizeof(data->scan), pf->timestamp);
 	mutex_unlock(&data->mutex);
 
 	iio_trigger_notify_done(indio_dev->trig);
-- 
2.43.0

Re: [PATCH 3/3] iio: accel: bmc150: use iio_push_to_buffers_with_ts()

[Linus Walleij]

On Fri, Aug 14, 2026 at 12:19 PM Yash Suthar <yashsuthar983@gmail.com> wrote:

> Replace deprecated iio_push_to_buffers_with_timestamp() with
> iio_push_to_buffers_with_ts() to allow source size runtime checks.
>
> Suggested-by: David Lechner <dlechner@baylibre.com>
> Signed-off-by: Yash Suthar <yashsuthar983@gmail.com>

Reviewed-by: Linus Walleij <linusw@kernel.org>

Yours,
Linus Walleij