@@ -975,48 +975,37 @@ static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx,
struct spi_transfer *transfer)
{
struct dma_async_tx_descriptor *desc_tx = NULL, *desc_rx = NULL;
- int ret;
unsigned long transfer_timeout;
unsigned long timeout;
struct spi_master *master = spi_imx->bitbang.master;
struct sg_table *tx = &transfer->tx_sg, *rx = &transfer->rx_sg;
- if (tx) {
- desc_tx = dmaengine_prep_slave_sg(master->dma_tx,
- tx->sgl, tx->nents, DMA_MEM_TO_DEV,
- DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
- if (!desc_tx)
- return -EINVAL;
-
- desc_tx->callback = spi_imx_dma_tx_callback;
- desc_tx->callback_param = (void *)spi_imx;
- dmaengine_submit(desc_tx);
- }
+ /*
+ * The TX DMA setup starts the transfer, so make sure RX is configured
+ * before TX.
+ */
+ desc_rx = dmaengine_prep_slave_sg(master->dma_rx,
+ rx->sgl, rx->nents, DMA_DEV_TO_MEM,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ if (!desc_rx)
+ return -EINVAL;
- if (rx) {
- desc_rx = dmaengine_prep_slave_sg(master->dma_rx,
- rx->sgl, rx->nents, DMA_DEV_TO_MEM,
- DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
- if (!desc_rx)
- return -EINVAL;
+ desc_rx->callback = spi_imx_dma_rx_callback;
+ desc_rx->callback_param = (void *)spi_imx;
+ dmaengine_submit(desc_rx);
+ reinit_completion(&spi_imx->dma_rx_completion);
+ dma_async_issue_pending(master->dma_rx);
- desc_rx->callback = spi_imx_dma_rx_callback;
- desc_rx->callback_param = (void *)spi_imx;
- dmaengine_submit(desc_rx);
- }
+ desc_tx = dmaengine_prep_slave_sg(master->dma_tx,
+ tx->sgl, tx->nents, DMA_MEM_TO_DEV,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ if (!desc_tx)
+ return -EINVAL;
- reinit_completion(&spi_imx->dma_rx_completion);
+ desc_tx->callback = spi_imx_dma_tx_callback;
+ desc_tx->callback_param = (void *)spi_imx;
+ dmaengine_submit(desc_tx);
reinit_completion(&spi_imx->dma_tx_completion);
-
- /*
- * Set these order to avoid potential RX overflow. The overflow may
- * happen if we enable SPI HW before starting RX DMA due to rescheduling
- * for another task and/or interrupt.
- * So RX DMA enabled first to make sure data would be read out from FIFO
- * ASAP. TX DMA enabled next to start filling TX FIFO with new data.
- * And finaly SPI HW enabled to start actual data transfer.
- */
- dma_async_issue_pending(master->dma_rx);
dma_async_issue_pending(master->dma_tx);
transfer_timeout = spi_imx_calculate_timeout(spi_imx, transfer->len);
@@ -1028,22 +1017,19 @@ static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx,
dev_err(spi_imx->dev, "I/O Error in DMA TX\n");
dmaengine_terminate_all(master->dma_tx);
dmaengine_terminate_all(master->dma_rx);
- } else {
- timeout = wait_for_completion_timeout(
- &spi_imx->dma_rx_completion, transfer_timeout);
- if (!timeout) {
- dev_err(spi_imx->dev, "I/O Error in DMA RX\n");
- spi_imx->devtype_data->reset(spi_imx);
- dmaengine_terminate_all(master->dma_rx);
- }
+ return -ETIMEDOUT;
}
- if (!timeout)
- ret = -ETIMEDOUT;
- else
- ret = transfer->len;
+ timeout = wait_for_completion_timeout(&spi_imx->dma_rx_completion,
+ transfer_timeout);
+ if (!timeout) {
+ dev_err(&master->dev, "I/O Error in DMA RX\n");
+ spi_imx->devtype_data->reset(spi_imx);
+ dmaengine_terminate_all(master->dma_rx);
+ return -ETIMEDOUT;
+ }
- return ret;
+ return transfer->len;
}
static int spi_imx_pio_transfer(struct spi_device *spi,
The driver tries to be clever by only setting up DMA channels when the corresponding sg tables are non NULL. The sg tables are embedded structs in struct spi_transfer, so they are guaranteed to be non NULL which makes the if(tx)/if(rx) tests completely bogus. The driver even sets the SPI_MASTER_MUST_RX / SPI_MASTER_MUST_TX flags which makes sure the sg tables are not only present but also non empty. Drop the tests and make the DMA path easier to follow. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> --- drivers/spi/spi-imx.c | 78 +++++++++++++++++++++------------------------------ 1 file changed, 32 insertions(+), 46 deletions(-)