[PATCH v1 RFC 2/2] spi: spi-imx: add fallback feature

[Robin Gong <yibin.gong@nxp.com>]

Add fallback pio feature for dma transfer failed. Since another whole
pio transfer including setup_transfer will be issued by spi core, no
need to restore jobs like commit bcd8e7761ec9 ("spi: imx: fallback to PIO
if dma setup failure").

Signed-off-by: Robin Gong <yibin.gong@nxp.com>
---
 drivers/spi/spi-imx.c | 23 +++++------------------
 1 file changed, 5 insertions(+), 18 deletions(-)

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index b7a85e3..afd31d7 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -224,7 +224,7 @@ static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi,
 {
 	struct spi_imx_data *spi_imx = spi_master_get_devdata(master);
 
-	if (!use_dma)
+	if (!use_dma || master->fallback)
 		return false;
 
 	if (!master->dma_rx)
@@ -1302,7 +1302,8 @@ static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx,
 	master->can_dma = spi_imx_can_dma;
 	master->max_dma_len = MAX_SDMA_BD_BYTES;
 	spi_imx->bitbang.master->flags = SPI_MASTER_MUST_RX |
-					 SPI_MASTER_MUST_TX;
+					 SPI_MASTER_MUST_TX |
+					 SPI_MASTER_FALLBACK;
 
 	return 0;
 err:
@@ -1507,7 +1508,6 @@ static int spi_imx_transfer(struct spi_device *spi,
 				struct spi_transfer *transfer)
 {
 	struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
-	int ret;
 
 	/* flush rxfifo before transfer */
 	while (spi_imx->devtype_data->rx_available(spi_imx))
@@ -1516,21 +1516,8 @@ static int spi_imx_transfer(struct spi_device *spi,
 	if (spi_imx->slave_mode)
 		return spi_imx_pio_transfer_slave(spi, transfer);
 
-	/*
-	 * fallback PIO mode if dma setup error happen, for example sdma
-	 * firmware may not be updated as ERR009165 required.
-	 */
-	if (spi_imx->usedma) {
-		ret = spi_imx_dma_transfer(spi_imx, transfer);
-		if (ret != -EINVAL)
-			return ret;
-
-		spi_imx->devtype_data->disable_dma(spi_imx);
-
-		spi_imx->usedma = false;
-		spi_imx->dynamic_burst = spi_imx->devtype_data->dynamic_burst;
-		dev_dbg(&spi->dev, "Fallback to PIO mode\n");
-	}
+	if (spi_imx->usedma)
+		return spi_imx_dma_transfer(spi_imx, transfer);
 
 	return spi_imx_pio_transfer(spi, transfer);
 }
-- 
2.7.4