sdma_write
sdma_write(b, SDMA_TCR + i * sizeof(uint32_t), 0);
sdma_write(b, SDMA_INT_MASK, b->int_mask);
sdma_write(b, SDMA_INT_PEND, SDMA_INT_IMPL);
sdma_write(b, SDMA_TASKBAR, pa);
sdma_write(b, SDMA_INT_MASK, b->int_mask);
sdma_write(b, SDMA_INT_MASK, b->int_mask);
sdma_write(b, SDMA_INT_PEND, SDMA_INT_TASK(irq));