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| author | Geert Uytterhoeven <geert+renesas@glider.be> | 2014-07-09 12:26:22 +0200 |
|---|---|---|
| committer | Mark Brown <broonie@linaro.org> | 2014-07-16 22:41:12 +0100 |
| commit | 85912a88c1ebcad04a5cfec971771195ce8d6691 (patch) | |
| tree | c52411154cd1c2443f9c51cc43fbdd324853c6f6 | |
| parent | 533465a8f8a969bac17550fc6f42cea1dfaa095f (diff) | |
| download | linux-85912a88c1ebcad04a5cfec971771195ce8d6691.tar.gz linux-85912a88c1ebcad04a5cfec971771195ce8d6691.tar.bz2 linux-85912a88c1ebcad04a5cfec971771195ce8d6691.zip | |
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>
| -rw-r--r-- | drivers/spi/spi-rspi.c | 30 |
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); } |