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authorGeert Uytterhoeven <geert+renesas@glider.be>2014-07-09 14:26:22 +0400
committerMark Brown <broonie@linaro.org>2014-07-17 01:41:12 +0400
commit85912a88c1ebcad04a5cfec971771195ce8d6691 (patch)
treec52411154cd1c2443f9c51cc43fbdd324853c6f6 /drivers/spi/spi-rspi.c
parent533465a8f8a969bac17550fc6f42cea1dfaa095f (diff)
downloadlinux-85912a88c1ebcad04a5cfec971771195ce8d6691.tar.xz
spi: rspi: Handle dmaengine_prep_slave_sg() failures gracefully
As typically a shmobile SoC has less DMA channels than devices that can use DMA, we may want to prioritize access to the DMA channels in the future. This means that dmaengine_prep_slave_sg() may start failing arbitrarily. Handle dmaengine_prep_slave_sg() failures gracefully by falling back to PIO. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mark Brown <broonie@linaro.org>
Diffstat (limited to 'drivers/spi/spi-rspi.c')
-rw-r--r--drivers/spi/spi-rspi.c30
1 files changed, 22 insertions, 8 deletions
diff --git a/drivers/spi/spi-rspi.c b/drivers/spi/spi-rspi.c
index 38fd938d6360..c850dfdfa9e3 100644
--- a/drivers/spi/spi-rspi.c
+++ b/drivers/spi/spi-rspi.c
@@ -477,7 +477,7 @@ static int rspi_dma_transfer(struct rspi_data *rspi, struct sg_table *tx,
tx->sgl, tx->nents, DMA_TO_DEVICE,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!desc_tx)
- return -EIO;
+ goto no_dma;
irq_mask |= SPCR_SPTIE;
}
@@ -486,7 +486,7 @@ static int rspi_dma_transfer(struct rspi_data *rspi, struct sg_table *tx,
rx->sgl, rx->nents, DMA_FROM_DEVICE,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!desc_rx)
- return -EIO;
+ goto no_dma;
irq_mask |= SPCR_SPRIE;
}
@@ -540,6 +540,12 @@ static int rspi_dma_transfer(struct rspi_data *rspi, struct sg_table *tx,
enable_irq(rspi->rx_irq);
return ret;
+
+no_dma:
+ pr_warn_once("%s %s: DMA not available, falling back to PIO\n",
+ dev_driver_string(&rspi->master->dev),
+ dev_name(&rspi->master->dev));
+ return -EAGAIN;
}
static void rspi_receive_init(const struct rspi_data *rspi)
@@ -593,8 +599,10 @@ static int rspi_common_transfer(struct rspi_data *rspi,
if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer)) {
/* rx_buf can be NULL on RSPI on SH in TX-only Mode */
- return rspi_dma_transfer(rspi, &xfer->tx_sg,
- xfer->rx_buf ? &xfer->rx_sg : NULL);
+ ret = rspi_dma_transfer(rspi, &xfer->tx_sg,
+ xfer->rx_buf ? &xfer->rx_sg : NULL);
+ if (ret != -EAGAIN)
+ return ret;
}
ret = rspi_pio_transfer(rspi, xfer->tx_buf, xfer->rx_buf, xfer->len);
@@ -648,8 +656,11 @@ static int qspi_transfer_out(struct rspi_data *rspi, struct spi_transfer *xfer)
{
int ret;
- if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer))
- return rspi_dma_transfer(rspi, &xfer->tx_sg, NULL);
+ if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer)) {
+ ret = rspi_dma_transfer(rspi, &xfer->tx_sg, NULL);
+ if (ret != -EAGAIN)
+ return ret;
+ }
ret = rspi_pio_transfer(rspi, xfer->tx_buf, NULL, xfer->len);
if (ret < 0)
@@ -663,8 +674,11 @@ static int qspi_transfer_out(struct rspi_data *rspi, struct spi_transfer *xfer)
static int qspi_transfer_in(struct rspi_data *rspi, struct spi_transfer *xfer)
{
- if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer))
- return rspi_dma_transfer(rspi, NULL, &xfer->rx_sg);
+ if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer)) {
+ int ret = rspi_dma_transfer(rspi, NULL, &xfer->rx_sg);
+ if (ret != -EAGAIN)
+ return ret;
+ }
return rspi_pio_transfer(rspi, NULL, xfer->rx_buf, xfer->len);
}