Current version of HAL drivers optimize IRQ handler by using precalculated
DMA register address and stream bitshift instead of calculating it on every interrupt.
Since we skip call to `HAL_DMA_Init` on reused DMA, fields StreamBaseAddress and StreamIndex
of DMA handle are not initialized and thus leads to SegFault in `DMA_IRQHandler`.
HAL_DMA_Init is a big routine and we do not need to call it on each use of DMA
(ex.: series of I2C operations) and DMA_CalcBaseAndBitshift is really small and
releasing it increases code size by only 8 bytes.
The DMA state is always HAL_DMA_STATE_RESET because of the memset clearing
all the data, so prior to this patch HAL_DMA_DeInit was never called. Now
it is always called to make sure the DMA is properly reset.
The main thing is to change the DMA code in a way that the structure
DMA_Stream_TypeDef (which is similar to DMA_Channel_TypeDef on stm32l4)
is no longer used outside of dma.c, as this structure only exists for the
F4 series. Therefore I introduced a new structure (dma_descr_t) which
handles all DMA specific stuff for configuration. Further the periphery
(spi, i2c, sdcard, dac) does not need to know the internals of the dma.
Adds a lot of code, makes IRQs a bit less efficient, but is very useful
for debugging. Usage: pyb.irq_stats() returns a memory view that can be
read and written, eg:
list(pyb.irq_stats())
pyb.irq_stats()[0]
pyb.irq_stats()[0] = 0
The patch provides general IRQ_ENTER() and IRQ_EXIT() macros that can be
modified to provide further IRQ statistics if desired.
Turning on each DMA block increases the current consumption
by about 8 mA. This code adds an idle timer for each DMA
block and turns off the clocks when no streams are in use
for 128 msec. Having a small timeout allows for improved
performance when back-to-back transfers are being performed.
The 128 msec is basically a guess.
This removes hard-coded DMA init params from dma_init(), instead defining
these parameters in a DMA_InitTypeDef struct that gets passed as an
argument to dma_init()
This makes dma_init more generic so it can be used for I2S and SD Card,
which require different initialization parameters.
