[PATCH v2 1/7] iio: inv_mpu6050: Do burst reads using spi/i2c directly
From: Crestez Dan Leonard <hidden>
Date: 2016-05-18 15:04:33
Also in:
linux-i2c, linux-iio, lkml
Subsystem:
iio subsystem and drivers, invensense mpu-6050 imu driver, the rest · Maintainers:
Jonathan Cameron, Jean-Baptiste Maneyrol, Linus Torvalds
Using regmap_read_bulk is wrong because it assumes that a range of registers is being read. In our case reading from the fifo register will return multiple values but this is *not* auto-increment. This currently works by accident. Signed-off-by: Crestez Dan Leonard <redacted> --- drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c | 33 ++++++++++++++++++++++++++---- 1 file changed, 29 insertions(+), 4 deletions(-)
diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
index d070062..8455af0 100644
--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c@@ -21,6 +21,7 @@ #include <linux/interrupt.h> #include <linux/kfifo.h> #include <linux/poll.h> +#include <linux/spi/spi.h> #include "inv_mpu_iio.h" static void inv_clear_kfifo(struct inv_mpu6050_state *st)
@@ -128,6 +129,13 @@ irqreturn_t inv_mpu6050_read_fifo(int irq, void *p) u16 fifo_count; s64 timestamp; + struct device *regmap_dev = regmap_get_device(st->map); + struct i2c_client *i2c; + struct spi_device *spi = NULL; + + i2c = i2c_verify_client(regmap_dev); + spi = i2c ? NULL: to_spi_device(regmap_dev); + mutex_lock(&indio_dev->mlock); if (!(st->chip_config.accl_fifo_enable | st->chip_config.gyro_fifo_enable))
@@ -160,10 +168,27 @@ irqreturn_t inv_mpu6050_read_fifo(int irq, void *p) fifo_count / bytes_per_datum + INV_MPU6050_TIME_STAMP_TOR) goto flush_fifo; while (fifo_count >= bytes_per_datum) { - result = regmap_bulk_read(st->map, st->reg->fifo_r_w, - data, bytes_per_datum); - if (result) - goto flush_fifo; + /* + * We need to do a large burst read from a single register. + * + * regmap_read_bulk assumes that multiple registers are + * involved but in our case st->reg->fifo_r_w + 1 is something + * completely unrelated. + */ + if (spi) { + u8 cmd = st->reg->fifo_r_w | 0x80; + result = spi_write_then_read(spi, + &cmd, 1, + data, bytes_per_datum); + if (result) + goto flush_fifo; + } else { + result = i2c_smbus_read_i2c_block_data(i2c, + st->reg->fifo_r_w, + bytes_per_datum, data); + if (result != bytes_per_datum) + goto flush_fifo; + } result = kfifo_out(&st->timestamps, ×tamp, 1); /* when there is no timestamp, put timestamp as 0 */
--
2.5.5