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spicommon_dmaworkaround_req_reset() function
Request a reset for a certain DMA channel Essentially, when a reset is needed, a driver can request this using spicommon_dmaworkaround_req_reset. This is supposed to be called with an user-supplied function as an argument. If both DMA channels are idle, this call will reset the DMA subsystem and return true. If the other DMA channel is still busy, it will return false; as soon as the other DMA channel is done, however, it will reset the DMA subsystem and call the callback. The callback is then supposed to be used to continue the SPI drivers activity.
Syntax
Implemented in ![]()
spi_common.c:1020
Return value
True when a DMA reset could be executed immediately. False when it could not; in this case the callback will be called with the specified argument when the logic can execute a reset, after that reset.
Notes
In some (well-defined) cases in the ESP32 (at least rev v.0 and v.1), a SPI DMA channel will get confused. This can be remedied by resetting the SPI DMA hardware in case this happens. Unfortunately, the reset knob used for this will reset _both_ DMA channels, and as such can only done safely when both DMA channels are idle. These functions coordinate this.