iio: adis: add burst_max_speed_hz variable

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>
Link: https://lore.kernel.org/r/20210427085454.30616-5-nuno.sa@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/imu/adis_buffer.c b/drivers/iio/imu/adis_buffer.c
index f6dbfbd17d41b125662d4cf6b96fd93e47ce0986..351c303c8a8c05749957cbb8a05782e4ae3d2e68 100644 (file)
--- 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 f9b728d490b1f97225533a505ae12f7fbd22a922..cf49997d5903e9fc77cc5075f2eb2eda943dae8a 100644 (file)
--- 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;
 };
 
 /**