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Subject[PATCH v2 05/11] spi: dw-dma: Move DMA transfers submission to the channels prep methods
Date
Indeed we can freely move the dmaengine_submit() method invocation and the
Tx and Rx busy flag setting into the DMA Tx/Rx prepare methods. Since the
Tx/Rx preparation method is now mainly used for the DMA transfers
submission, here we suggest to rename it to have the _submit_{r,t}x suffix
instead.

By having this alteration applied first we implement another code
preparation before adding the one-by-one DMA SG entries transmission,
second we now have the dma_async_tx_descriptor descriptor used locally
only in the new DMA transfers submission methods (this will be cleaned up
a bit later), third we make the generic transfer method more readable,
where now the functionality of submission, execution and wait procedures
is transparently split up instead of having a preparation, intermixed
submission/execution and wait procedures.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
---
drivers/spi/spi-dw-dma.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/spi/spi-dw-dma.c b/drivers/spi/spi-dw-dma.c
index d2a67dee1a66..769d10ca74b4 100644
--- a/drivers/spi/spi-dw-dma.c
+++ b/drivers/spi/spi-dw-dma.c
@@ -272,7 +272,7 @@ static int dw_spi_dma_config_tx(struct dw_spi *dws)
}

static struct dma_async_tx_descriptor *
-dw_spi_dma_prepare_tx(struct dw_spi *dws, struct spi_transfer *xfer)
+dw_spi_dma_submit_tx(struct dw_spi *dws, struct spi_transfer *xfer)
{
struct dma_async_tx_descriptor *txdesc;

@@ -287,6 +287,9 @@ dw_spi_dma_prepare_tx(struct dw_spi *dws, struct spi_transfer *xfer)
txdesc->callback = dw_spi_dma_tx_done;
txdesc->callback_param = dws;

+ dmaengine_submit(txdesc);
+ set_bit(TX_BUSY, &dws->dma_chan_busy);
+
return txdesc;
}

@@ -364,7 +367,7 @@ static int dw_spi_dma_config_rx(struct dw_spi *dws)
return dmaengine_slave_config(dws->rxchan, &rxconf);
}

-static struct dma_async_tx_descriptor *dw_spi_dma_prepare_rx(struct dw_spi *dws,
+static struct dma_async_tx_descriptor *dw_spi_dma_submit_rx(struct dw_spi *dws,
struct spi_transfer *xfer)
{
struct dma_async_tx_descriptor *rxdesc;
@@ -380,6 +383,9 @@ static struct dma_async_tx_descriptor *dw_spi_dma_prepare_rx(struct dw_spi *dws,
rxdesc->callback = dw_spi_dma_rx_done;
rxdesc->callback_param = dws;

+ dmaengine_submit(rxdesc);
+ set_bit(RX_BUSY, &dws->dma_chan_busy);
+
return rxdesc;
}

@@ -426,25 +432,21 @@ static int dw_spi_dma_transfer(struct dw_spi *dws, struct spi_transfer *xfer)
struct dma_async_tx_descriptor *txdesc, *rxdesc;
int ret;

- /* Prepare the TX dma transfer */
- txdesc = dw_spi_dma_prepare_tx(dws, xfer);
+ /* Submit the DMA Tx transfer */
+ txdesc = dw_spi_dma_submit_tx(dws, xfer);
if (!txdesc)
return -EINVAL;

- /* Prepare the RX dma transfer */
+ /* Submit the DMA Rx transfer if required */
if (xfer->rx_buf) {
- rxdesc = dw_spi_dma_prepare_rx(dws, xfer);
+ rxdesc = dw_spi_dma_submit_rx(dws, xfer);
if (!rxdesc)
return -EINVAL;

/* rx must be started before tx due to spi instinct */
- set_bit(RX_BUSY, &dws->dma_chan_busy);
- dmaengine_submit(rxdesc);
dma_async_issue_pending(dws->rxchan);
}

- set_bit(TX_BUSY, &dws->dma_chan_busy);
- dmaengine_submit(txdesc);
dma_async_issue_pending(dws->txchan);

ret = dw_spi_dma_wait(dws, xfer);
--
2.27.0
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