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stm32/dma: Fix re-start of DMA stream by clearing all event flags. 

As per the datasheet, all event flags for a stream must be cleared before
enabling it.  Fixes issue #4944 (with DAC.write_timed).
This commit is contained in:
Damien George 2019-07-25 15:16:57 +10:00
parent e9593d5075
commit b1129df478
1 changed files with 24 additions and 0 deletions
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24
ports/stm32/dma.c
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@ -922,6 +922,30 @@ void dma_nohal_deinit(const dma_descr_t *descr) {
}
void dma_nohal_start(const dma_descr_t *descr, uint32_t src_addr, uint32_t dst_addr, uint16_t len) {
// Must clear all event flags for this stream before enabling it
DMA_TypeDef *dma_ctrl;
uint32_t ch = descr->id;
if (ch < NSTREAMS_PER_CONTROLLER) {
dma_ctrl = DMA1;
} else {
dma_ctrl = DMA2;
ch -= NSTREAMS_PER_CONTROLLER;
}
__IO uint32_t *ifcr;
if (ch <= 3) {
ifcr = &dma_ctrl->LIFCR;
} else {
ifcr = &dma_ctrl->HIFCR;
ch -= 4;
}
if (ch <= 1) {
ch = ch * 6;
} else {
ch = 4 + ch * 6;
}
*ifcr = 0x3d << ch;
// Configure and enable stream
DMA_Stream_TypeDef *dma = descr->instance;
dma->CR &= ~DMA_SxCR_DBM;
dma->NDTR = len;