STM32F4XX HAL: stopping ADC DMA can incorrectly return error

[davedesro]

Overview
HAL_ADC_Stop_DMA() can incorrectly return HAL_DMA_ERROR_NO_XFER and may not properly stop the DMA engine.

Target
stm32f4xx. I found this on the Nucleo_F446RE

other thoughts
If there is an abort request while DMA is not busy, should it really be considered an ERROR? Maybe instead it should just return HAL_OK. Any thoughts?

[davedesro]

Same behavior exists with the following

• stm32f7xx
• stm32l4xx
• stm32f2xx

The code in question is here:
stm32f4xx_hal_dma.c

[LMESTM]

@pliny When you mention that it may not properly stop the DMA, can you explicitly mention the DMA state and where this can happen ? Typically, what was the DMA HAL state when you've encountered the error ?

[LMESTM]

I have also transferred your question to DMA team, I'll keep you posted

[davedesro]

Hi @LMESTM , thanks for the quick response.

__HAL_DMA_DISABLE(hdma) will never get called unless there is an explicit HAL_DMA_DeInit() call or there's an error condition on interrupt. Currently, there's no clean way to disable the DMA without resetting the DMA engine.

Similarly, transfer related interrupts will not get disabled.

To me, it seems as if HAL_DMA_Abort() is treated as a dma disable call in stm32f4xx_hal_adc.c#L1154 instead of a conditional abort call.

I'm curious to know why this check exists stm32f4xx_hal_dma.c.

If it needs to be there, maybe the conditional could be

if(hdma->State == HAL_DMA_STATE_READY)

This assumes HAL_DMA_STATE_READY states that the system is idle, yet enabled, and that interrupts are disabled.

[davedesro]

Ah, I just realized I didn't really satisfy your request :)

you can set up a test with the following pseudocode

configure_clocks_and_pins()
configure_nonblocking_adc(&AdcHandle)
configure_dma(&DmaHandle)
__HAL_LINKDMA()
configure_nvic()
HAL_DMA_Init(&DmaHandle)
HAL_ADC_Init(&AdcHandle)

HAL_ADC_Start_DMA();
while(poll_for_mem0_ready()) {}
HAL_ADC_Stop_DMA();

HAL_ADC_Start_DMA(); /*< Here, you will get both a DMA and ADC error */

[bcostm]

ST_INTERNAL_REF 33814

[LMESTM]

@pliny Hi - our HAL team is asking if you could provide the ADC configuration that you are using ?

[davedesro]

Hi, this issue went away with this checkin: 42f66ee

[LMESTM]

@pliny ok thanks, then please close the issue