From 5423e4966c857c7d02c08f87fd872ddfbe8afc20 Mon Sep 17 00:00:00 2001 From: Jeff Epler Date: Mon, 8 Feb 2021 08:35:07 -0600 Subject: [PATCH] rp2pio: Transfer up to 32 bytes before checking background tasks @Jerryneedell noticed that this problem affected strips short enough to not use the DMA peripheral, thanks for the hot tip! Instead of checking for background tasks after every byte transfer, try up to 32 transfers before attending to background tasks. This fixes the problem I was seeing on my 5-pixel circuit. Closes #4135. --- .../common-hal/rp2pio/StateMachine.c | 26 ++++++++++++------- 1 file changed, 17 insertions(+), 9 deletions(-) diff --git a/ports/raspberrypi/common-hal/rp2pio/StateMachine.c b/ports/raspberrypi/common-hal/rp2pio/StateMachine.c index 6510410b0e..90c48130e1 100644 --- a/ports/raspberrypi/common-hal/rp2pio/StateMachine.c +++ b/ports/raspberrypi/common-hal/rp2pio/StateMachine.c @@ -546,15 +546,23 @@ static bool _transfer(rp2pio_statemachine_obj_t *self, size_t tx_remaining = out_len; while (rx_remaining || tx_remaining) { - if (tx_remaining && !pio_sm_is_tx_fifo_full(self->pio, self->state_machine)) { - *tx_destination = *data_out; - data_out++; - --tx_remaining; - } - if (rx_remaining && !pio_sm_is_rx_fifo_empty(self->pio, self->state_machine)) { - *data_in = (uint8_t) *rx_source; - data_in++; - --rx_remaining; + for (int i=0; i<32; i++) { + bool did_transfer = false; + if (tx_remaining && !pio_sm_is_tx_fifo_full(self->pio, self->state_machine)) { + *tx_destination = *data_out; + data_out++; + --tx_remaining; + did_transfer = true; + } + if (rx_remaining && !pio_sm_is_rx_fifo_empty(self->pio, self->state_machine)) { + *data_in = (uint8_t) *rx_source; + data_in++; + --rx_remaining; + did_transfer = true; + } + if (!did_transfer) { + break; + } } RUN_BACKGROUND_TASKS; if (mp_hal_is_interrupted()) {