From 454c219f5d8452eff87b701735ae1224f4410356 Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Mon, 22 Mar 2021 14:24:08 +0100 Subject: iio: imu: inv_mpu6050: Use as standalone trigger It may happen that the MPU6050 is the only hardware trigger available on your system such as this: > lsiio Device 003: hscdtd008a Device 001: mpu6050 Device 002: gp2ap002 Device 000: ab8500-gpadc Trigger 000: mpu6050-dev1 And when you want to use it to read periodically from your magnetometer like this: > iio_generic_buffer -a -c 100 -n hscdtd008a -t mpu6050-dev1 Then the following happens: [ 209.951334] Internal error: Oops: 5 [#1] SMP ARM (...) [ 209.981969] Hardware name: ST-Ericsson Ux5x0 platform (Device Tree Support) [ 209.988925] PC is at inv_scan_query_mpu6050+0x8/0xb8 [ 209.993914] LR is at inv_mpu6050_set_enable+0x40/0x194 This is because since we are not using any channels from the same device, the indio_dev->active_scan_mask is NULL. Just checking for that and bailing out is however not enough: we have to enable some kind of FIFO for the readout to work. So enable the temperature as a dummy FIFO and all works fine. Not suitable for backporting to stable. It is an odd corner case and does not represent a regression. Fixes: 09a642b78523 ("Invensense MPU6050 Device Driver.") Cc: Jean-Baptiste Maneyrol Signed-off-by: Linus Walleij Acked-by: Jean-Baptiste Maneyrol Link: https://lore.kernel.org/r/20210322132408.1003443-1-linus.walleij@linaro.org Signed-off-by: Jonathan Cameron --- drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'drivers/iio/imu') diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c index f7b5a70be30f..de8ed1446d60 100644 --- a/drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c +++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_trigger.c @@ -11,6 +11,16 @@ static unsigned int inv_scan_query_mpu6050(struct iio_dev *indio_dev) struct inv_mpu6050_state *st = iio_priv(indio_dev); unsigned int mask; + /* + * If the MPU6050 is just used as a trigger, then the scan mask + * is not allocated so we simply enable the temperature channel + * as a dummy and bail out. + */ + if (!indio_dev->active_scan_mask) { + st->chip_config.temp_fifo_enable = true; + return INV_MPU6050_SENSOR_TEMP; + } + st->chip_config.gyro_fifo_enable = test_bit(INV_MPU6050_SCAN_GYRO_X, indio_dev->active_scan_mask) || -- cgit v1.2.3-59-g8ed1b