| From 8efccf0ca3ccebdcea5e33bafd88ab1bdbea45f2 Mon Sep 17 00:00:00 2001 |
| From: Geert Uytterhoeven <geert+renesas@glider.be> |
| Date: Wed, 9 Jul 2014 12:26:22 +0200 |
| Subject: 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> |
| (cherry picked from commit 85912a88c1ebcad04a5cfec971771195ce8d6691) |
| Signed-off-by: Simon Horman <horms+renesas@verge.net.au> |
| --- |
| drivers/spi/spi-rspi.c | 30 ++++++++++++++++++++++-------- |
| 1 file 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); |
| } |
| -- |
| 2.1.2 |
| |