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Revert "drivers: dma: sam0: fix DMA to peripheral transfer on SAMD5x"

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This reverts commit 90cc723e65.

Using `DMAC_CHCTRLA_TRIGACT_BLOCK` breaks SERCOM UART peripheral DMA
operations (DMA-based asynchronous UART transmit operation only sends
the first byte and does not proceed any further).

The `DMAC_CHCTRLA_TRIGACT_BURST` with `DMAC_CHCTRLA_BURSTLEN(0)` is a
special case utilising the "internal FIFO", according to the datasheet
(see DS60001507E; 22.6.2.8), and should always be specified for
peripheral data transfer operations.

Also it is worth noting that Atmel and other third-party drivers use
the aforementioned "internal FIFO" configuration for peripheral data
transfers as well.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>
This commit is contained in:
Stephanos Ioannidis 2020-04-22 14:59:06 +09:00 • committed by Maureen Helm
commit 2a710b1372
1 changed files with 17 additions and 1 deletions
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18
drivers/dma/dma_sam0.c
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@ -151,7 +151,7 @@ static int dma_sam0_config(struct device *dev, u32_t channel,
DMAC_CHCTRLA_TRIGSRC(config->dma_slot);
} else {
/* One peripheral trigger per beat */
chcfg->CHCTRLA.reg = DMAC_CHCTRLA_TRIGACT_BLOCK |
chcfg->CHCTRLA.reg = DMAC_CHCTRLA_TRIGACT_BURST |
DMAC_CHCTRLA_TRIGSRC(config->dma_slot);
}
@ -163,6 +163,22 @@ static int dma_sam0_config(struct device *dev, u32_t channel,
chcfg->CHPRILVL.bit.PRILVL = config->channel_priority;
/* Set the burst length */
if (config->source_burst_length != config->dest_burst_length) {
LOG_ERR("Source and destination burst lengths must be equal");
goto inval;
}
if (config->source_burst_length > 16U) {
LOG_ERR("Invalid burst length");
goto inval;
}
if (config->source_burst_length > 0U) {
chcfg->CHCTRLA.reg |= DMAC_CHCTRLA_BURSTLEN(
config->source_burst_length - 1U);
}
/* Enable the interrupts */
chcfg->CHINTENSET.reg = DMAC_CHINTENSET_TCMPL;
if (!config->error_callback_en) {