diff mbox

[04/12] spi: imx: drop fallback to PIO

Message ID 1455867792-26389-5-git-send-email-s.hauer@pengutronix.de (mailing list archive)
State New, archived
Headers show

Commit Message

Sascha Hauer Feb. 19, 2016, 7:43 a.m. UTC 
At the moment the driver decides to fallback to PIO mode the buffers
are already mapped for DMA. It's a bug to access them with the CPU
afterwards, so we cannot just fallback to PIO mode.
It should not be necessary anyway, since we only use DMA when we
verified that it's possible in the fist place, so when prep_slave_sg
fails it's a bug, either in the SDMA driver or in the can_dma
implementation.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 drivers/spi/spi-imx.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

Comments

Mark Brown Feb. 19, 2016, 3:51 p.m. UTC | #1 
On Fri, Feb 19, 2016 at 08:43:04AM +0100, Sascha Hauer wrote:
> At the moment the driver decides to fallback to PIO mode the buffers
> are already mapped for DMA. It's a bug to access them with the CPU
> afterwards, so we cannot just fallback to PIO mode.

This doesn't apply against current code, please check and resend.
diff mbox

Patch

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index b277375..5a48d07 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -945,7 +945,7 @@  static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx,
 					tx->sgl, tx->nents, DMA_MEM_TO_DEV,
 					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 		if (!desc_tx)
-			goto no_dma;
+			return -EINVAL;
 
 		desc_tx->callback = spi_imx_dma_tx_callback;
 		desc_tx->callback_param = (void *)spi_imx;
@@ -957,7 +957,7 @@  static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx,
 					rx->sgl, rx->nents, DMA_DEV_TO_MEM,
 					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 		if (!desc_rx)
-			goto no_dma;
+			return -EINVAL;
 
 		desc_rx->callback = spi_imx_dma_rx_callback;
 		desc_rx->callback_param = (void *)spi_imx;
@@ -1010,10 +1010,6 @@  static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx,
 		ret = transfer->len;
 
 	return ret;
-
-no_dma:
-	dev_warn_once(spi_imx->dev, "DMA not available, falling back to PIO\n");
-	return -EAGAIN;
 }
 
 static int spi_imx_pio_transfer(struct spi_device *spi,
@@ -1040,15 +1036,12 @@  static int spi_imx_pio_transfer(struct spi_device *spi,
 static int spi_imx_transfer(struct spi_device *spi,
 				struct spi_transfer *transfer)
 {
-	int ret;
 	struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
 
 	if (spi_imx->bitbang.master->can_dma &&
 	    spi_imx_can_dma(spi_imx->bitbang.master, spi, transfer)) {
 		spi_imx->usedma = true;
-		ret = spi_imx_dma_transfer(spi_imx, transfer);
-		if (ret != -EAGAIN)
-			return ret;
+		return spi_imx_dma_transfer(spi_imx, transfer);
 	}
 	spi_imx->usedma = false;