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Subject[PATCH v2 03/11] spi: dw-dma: Configure the DMA channels in dma_setup
Date
Mainly this is a preparation patch before adding one-by-one DMA SG entries
transmission. But logically the Tx and Rx DMA channels setup should be
performed in the dma_setup() callback anyway. So we'll move the DMA slave
channels src/dst burst lengths, address and address width configuration
from the Tx/Rx channels preparation methods to the dedicated functions and
then make sure it's called at the DMA setup stage.

Note we now make sure the return value of the dmaengine_slave_config()
method doesn't indicate an error. It has been unnecessary in case if Dw
DMAC is utilized as a DMA engine, since its device_config() callback
always returns zero (though it might change in future). But since DW APB
SSI driver now supports any DMA back-end we must make sure the DMA device
configuration has been successful before proceeding with further setups.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
---
drivers/spi/spi-dw-dma.c | 42 +++++++++++++++++++++++++++++-----------
1 file changed, 31 insertions(+), 11 deletions(-)

diff --git a/drivers/spi/spi-dw-dma.c b/drivers/spi/spi-dw-dma.c
index 1b013ac94a3f..da17897b8acb 100644
--- a/drivers/spi/spi-dw-dma.c
+++ b/drivers/spi/spi-dw-dma.c
@@ -256,11 +256,9 @@ static void dw_spi_dma_tx_done(void *arg)
complete(&dws->dma_completion);
}

-static struct dma_async_tx_descriptor *
-dw_spi_dma_prepare_tx(struct dw_spi *dws, struct spi_transfer *xfer)
+static int dw_spi_dma_config_tx(struct dw_spi *dws)
{
struct dma_slave_config txconf;
- struct dma_async_tx_descriptor *txdesc;

memset(&txconf, 0, sizeof(txconf));
txconf.direction = DMA_MEM_TO_DEV;
@@ -270,7 +268,13 @@ dw_spi_dma_prepare_tx(struct dw_spi *dws, struct spi_transfer *xfer)
txconf.dst_addr_width = dw_spi_dma_convert_width(dws->n_bytes);
txconf.device_fc = false;

- dmaengine_slave_config(dws->txchan, &txconf);
+ return dmaengine_slave_config(dws->txchan, &txconf);
+}
+
+static struct dma_async_tx_descriptor *
+dw_spi_dma_prepare_tx(struct dw_spi *dws, struct spi_transfer *xfer)
+{
+ struct dma_async_tx_descriptor *txdesc;

txdesc = dmaengine_prep_slave_sg(dws->txchan,
xfer->tx_sg.sgl,
@@ -345,14 +349,9 @@ static void dw_spi_dma_rx_done(void *arg)
complete(&dws->dma_completion);
}

-static struct dma_async_tx_descriptor *dw_spi_dma_prepare_rx(struct dw_spi *dws,
- struct spi_transfer *xfer)
+static int dw_spi_dma_config_rx(struct dw_spi *dws)
{
struct dma_slave_config rxconf;
- struct dma_async_tx_descriptor *rxdesc;
-
- if (!xfer->rx_buf)
- return NULL;

memset(&rxconf, 0, sizeof(rxconf));
rxconf.direction = DMA_DEV_TO_MEM;
@@ -362,7 +361,16 @@ static struct dma_async_tx_descriptor *dw_spi_dma_prepare_rx(struct dw_spi *dws,
rxconf.src_addr_width = dw_spi_dma_convert_width(dws->n_bytes);
rxconf.device_fc = false;

- dmaengine_slave_config(dws->rxchan, &rxconf);
+ return dmaengine_slave_config(dws->rxchan, &rxconf);
+}
+
+static struct dma_async_tx_descriptor *dw_spi_dma_prepare_rx(struct dw_spi *dws,
+ struct spi_transfer *xfer)
+{
+ struct dma_async_tx_descriptor *rxdesc;
+
+ if (!xfer->rx_buf)
+ return NULL;

rxdesc = dmaengine_prep_slave_sg(dws->rxchan,
xfer->rx_sg.sgl,
@@ -381,10 +389,22 @@ static struct dma_async_tx_descriptor *dw_spi_dma_prepare_rx(struct dw_spi *dws,
static int dw_spi_dma_setup(struct dw_spi *dws, struct spi_transfer *xfer)
{
u16 imr, dma_ctrl;
+ int ret;

if (!xfer->tx_buf)
return -EINVAL;

+ /* Setup DMA channels */
+ ret = dw_spi_dma_config_tx(dws);
+ if (ret)
+ return ret;
+
+ if (xfer->rx_buf) {
+ ret = dw_spi_dma_config_rx(dws);
+ if (ret)
+ return ret;
+ }
+
/* Set the DMA handshaking interface */
dma_ctrl = SPI_DMA_TDMAE;
if (xfer->rx_buf)
--
2.27.0
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