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dshot: fix bidirectional dshot stream sharing (#24996)

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Freeing the DMA stream in the hrt callback causes other peripherals on that DMA controller to lock up (namely GPS). Moving the free back into thread context, right before allocation, solves the problem
This commit is contained in:
Jacob Dahl
2025-06-10 00:36:45 -08:00
committed by GitHub
parent 6e7638c14b
commit bb423bc007
1 changed files with 22 additions and 14 deletions
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20
platforms/nuttx/src/px4/stm/stm32_common/dshot/dshot.c
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@@ -206,7 +206,7 @@ static void init_timers_dma_up(void)
timer_configs[timer_index].dma_handle = stm32_dmachannel(io_timers[timer_index].dshot.dma_map_up);
if (timer_configs[timer_index].dma_handle == NULL) {
PX4_DEBUG("Failed to allocate Timer %u DMA UP", timer_index);
PX4_WARN("Failed to allocate Timer %u DMA UP", timer_index);
continue;
}
@@ -214,6 +214,9 @@ static void init_timers_dma_up(void)
timer_configs[timer_index].initialized = true;
}
// Bidirectional DShot will free/allocate DMA stream on every update event. This is required
// in order to reconfigure the DMA stream between Timer Burst and CaptureCompare.
if (_bidirectional) {
// Free the allocated DMA channels
for (uint8_t timer_index = 0; timer_index < MAX_IO_TIMERS; timer_index++) {
if (timer_configs[timer_index].dma_handle != NULL) {
@@ -222,6 +225,7 @@ static void init_timers_dma_up(void)
PX4_INFO("Freed DMA UP Timer Index %u", timer_index);
}
}
}
}
static int32_t init_timer_channels(uint8_t timer_index)
@@ -341,8 +345,15 @@ void up_dshot_trigger()
io_timer_set_dshot_burst_mode(timer_index, _dshot_frequency, channel_count);
if (_bidirectional) {
// Deallocate DMA from previous transaction
if (timer_configs[timer_index].dma_handle != NULL) {
stm32_dmastop(timer_configs[timer_index].dma_handle);
stm32_dmafree(timer_configs[timer_index].dma_handle);
timer_configs[timer_index].dma_handle = NULL;
}
// Allocate DMA
if (timer_configs[timer_index].dma_handle == NULL) {
timer_configs[timer_index].dma_handle = stm32_dmachannel(io_timers[timer_index].dshot.dma_map_up);
if (timer_configs[timer_index].dma_handle == NULL) {
@@ -502,11 +513,8 @@ static void capture_complete_callback(void *arg)
// Disable capture DMA
io_timer_capture_dma_req(timer_index, capture_channel, false);
if (timer_configs[timer_index].dma_handle != NULL) {
// Stop DMA (should already be finished)
stm32_dmastop(timer_configs[timer_index].dma_handle);
stm32_dmafree(timer_configs[timer_index].dma_handle);
timer_configs[timer_index].dma_handle = NULL;
}
// Re-initialize all output channels on this timer
for (uint8_t output_channel = 0; output_channel < MAX_TIMER_IO_CHANNELS; output_channel++) {