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STM32F4 SDIO DMA interrupts not triggered in another interrupt

Question asked by woley.davy on Nov 15, 2013
I have been busy these past days trying to understand a problem revolving around this simple algorithm :
every second write a byte through SDIO using ST DMA2 example.
Using a simple loop in main works perfectly :
while(1) file.write(1);
But using a TIM interrupt fails :
void TIM7_IRQHandler(void) { file.write(1); }
The operation hangs in :
SD_WaitReadOperation(void) first while loop checking for the DMA transfer end :

while ((DMAEndOfTransfer == 0x00) && (TransferEnd == 0) && (TransferError == SD_OK) && (timeout > 0))
It seems the DMA2 interrupts aren't triggered when the context is the TIM interrupt.

The preemption priorities are :

         - SDIO_IRQn : 0 (ST example),
         - SDIO SD_SDIO_DMA_IRQn: 1 (ST example),
         - TIM_IRQn : 11.

The MCU is STM32F407VET6 and DMA is only used for SDIO. The same problem happens when the context is an USART interrupt.

Is this expected behaviour ?
Thank you very much !