The device number in /dev may not be reliable from one boot to another
due to the initialization order of each bus.
For example, in Minnow Board Max, the exposed I2C buses may be i2c-7 and
i2c-8 or i2c-8 and i2c-9 depending if the platform driver in the kernel
is initialized before or after the PCI.
It also may change with different version and configuration of the DT or
UEFI used making another kernel driver to bind to the device. This means that
for Minnow Board Max we need to use something like below to pass to the
constructor:
static const char * const i2c_devpaths[] = {
/* UEFI with lpss set to ACPI */
"/devices/platform/80860F41:05",
/* UEFI with lpss set to PCI */
"/devices/pci0000:00/0000:00:18.6",
NULL
};
The devpath here is the one returned by udev with the following command:
udevadm info -q path /dev/<i2c-device>
In contrary to the device number in /dev/i2c-N, this path in sysfs is
stable across reboots and can only change if there's a change in the
UEFI firmware or the board's device tree.
This patch assumes the currently supported boards don't have this
problem so it's not touching them.
- when resuming a mission we should read the value from storage of the same index to ensure we're not continuing an old cached version of the mission item.
- inherent problem: DO commands will continue and will be unaffected unless the new mission has a different DO_ command structure. If so, a set_current_cmd() or reset() should be issued by the GCS.
The previous implementation made some boards apply two rotations to suit
their default orientation. That was happening because there was an
unconditional rotation being done (commented as "rotate for bbone
default").
This commit makes that unconditional rotation as a default rotation
instead and adjusts the former additional rotations to be single
rotations.
As the datasheet says: "To prevent switching into I2C mode when using
SPI, the I2C interface should be disabled by setting the I2C_IF_DIS
configuration bit."
We also reset the sensor like PX4Firmware does for initializing the
MPU6000. See: ee1d8cd770/src/drivers/mpu6000/mpu6000.cpp (L695)
