- update to NuttX with stm32f4 and stm32f7 SPI DMA internal buffers
- remove explicit DMA buffer allocations from new IMU drivers
- restore original BOARD_DMA_ALLOC_POOL_SIZE
- decrease SPI DMA thresholds based on fmu-v2/v3/v4/v5 bench testing
On more complicated setups it's still possible to exceed 32 tasks. For example fmu-v5 with mavlink on every telem (+ USB), external spi usage (pmw3901), gimbal (vmount), multiple i2c sensors, and camera feedback is 35 tasks (with top running). This is a fairly extreme case, so I'm only going to increase CONFIG_MAX_TASKS on newer F7 boards.
But only on the first 4 FMU outputs, as the next ones conflict with px4io
serial dma (UART8_RX)
RX DMA is disabled on the GPS port as well (conflicts with TIM1).
