Closed IRISZZW closed 5 years ago
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device: spi_master: optimize the fix of spi cs auto toggle issue and add polling function for sub system spi master driver.
For currently supported arc boards, there is one issue that the cs pin of dw spi master & sub system spi master will toggle automacticall when spi tx fifo is empty.
the spi tx fifo can be empty by two reasons
the spi transfer is finished which is a correct case
the spi transfer is not finished, but spi fifo operation is interruptted by higher priority interrupts. This is a wrong case as the toggle of cs will confuse spi slave before spi transfer is finished.
to avoid reason 2
use other bit/pin to mast spi cs, e.g. emsk 2.2, hsdk
disable interrupts for poll based operations, e.g. emsdp
avoid interrupt preemption to spi mst interrupt for int based operations, e.g. iotdk.