[PATCH v3 4/6] iio: adis: add burst_max_speed_hz variable

[Nuno Sa <nuno.sa@analog.com>]

Typically, in burst mode, the device cannot operate at it's full spi
speed. Hence, the spi transfers for burst mode have to take this into
account. With this change we avoid a potential race with the spi core as
drivers were 'hacking' the device 'max_speed_hz' directly in the
trigger handler.

Reviewed-by: Alexandru Ardelean <ardeleanalex@gmail.com>
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
---
 drivers/iio/imu/adis_buffer.c | 4 ++++
 include/linux/iio/imu/adis.h  | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/drivers/iio/imu/adis_buffer.c b/drivers/iio/imu/adis_buffer.c
index f6dbfbd17d41..351c303c8a8c 100644
--- a/drivers/iio/imu/adis_buffer.c
+++ b/drivers/iio/imu/adis_buffer.c
@@ -51,9 +51,13 @@ static int adis_update_scan_mode_burst(struct iio_dev *indio_dev,
 	adis->xfer[0].tx_buf = tx;
 	adis->xfer[0].bits_per_word = 8;
 	adis->xfer[0].len = 2;
+	if (adis->data->burst_max_speed_hz)
+		adis->xfer[0].speed_hz = adis->data->burst_max_speed_hz;
 	adis->xfer[1].rx_buf = adis->buffer;
 	adis->xfer[1].bits_per_word = 8;
 	adis->xfer[1].len = burst_length;
+	if (adis->data->burst_max_speed_hz)
+		adis->xfer[1].speed_hz = adis->data->burst_max_speed_hz;
 
 	spi_message_init(&adis->msg);
 	spi_message_add_tail(&adis->xfer[0], &adis->msg);
diff --git a/include/linux/iio/imu/adis.h b/include/linux/iio/imu/adis.h
index f9b728d490b1..cf49997d5903 100644
--- a/include/linux/iio/imu/adis.h
+++ b/include/linux/iio/imu/adis.h
@@ -55,6 +55,7 @@ struct adis_timeout {
  *			this should be the minimum size supported by the device.
  * @burst_max_len:	Holds the maximum burst size when the device supports
  *			more than one burst mode with different sizes
+ * @burst_max_speed_hz:	Maximum spi speed that can be used in burst mode
  */
 struct adis_data {
 	unsigned int read_delay;
@@ -83,6 +84,7 @@ struct adis_data {
 	unsigned int burst_reg_cmd;
 	unsigned int burst_len;
 	unsigned int burst_max_len;
+	unsigned int burst_max_speed_hz;
 };
 
 /**
-- 
2.31.1