diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/spi/pxa2xx_spi.c | 57 |
1 files changed, 43 insertions, 14 deletions
diff --git a/drivers/spi/pxa2xx_spi.c b/drivers/spi/pxa2xx_spi.c index 147e26a78d6..54b2ae176be 100644 --- a/drivers/spi/pxa2xx_spi.c +++ b/drivers/spi/pxa2xx_spi.c @@ -48,9 +48,10 @@ MODULE_ALIAS("platform:pxa2xx-spi"); #define MAX_BUSES 3 -#define DMA_INT_MASK (DCSR_ENDINTR | DCSR_STARTINTR | DCSR_BUSERR) -#define RESET_DMA_CHANNEL (DCSR_NODESC | DMA_INT_MASK) -#define IS_DMA_ALIGNED(x) (((u32)(x)&0x07)==0) +#define DMA_INT_MASK (DCSR_ENDINTR | DCSR_STARTINTR | DCSR_BUSERR) +#define RESET_DMA_CHANNEL (DCSR_NODESC | DMA_INT_MASK) +#define IS_DMA_ALIGNED(x) (((x) & 0x07) == 0) +#define MAX_DMA_LEN 8191 /* * for testing SSCR1 changes that require SSP restart, basically @@ -846,14 +847,27 @@ static void pump_transfers(unsigned long data) udelay(previous->delay_usecs); } - /* Check transfer length */ - if (transfer->len > 8191) - { - dev_warn(&drv_data->pdev->dev, "pump_transfers: transfer " - "length greater than 8191\n"); - message->status = -EINVAL; - giveback(drv_data); - return; + /* Check for transfers that need multiple DMA segments */ + if (transfer->len > MAX_DMA_LEN && chip->enable_dma) { + + /* reject already-mapped transfers; PIO won't always work */ + if (message->is_dma_mapped + || transfer->rx_dma || transfer->tx_dma) { + dev_err(&drv_data->pdev->dev, + "pump_transfers: mapped transfer length " + "of %lu is greater than %d\n", + transfer->len, MAX_DMA_LEN); + message->status = -EINVAL; + giveback(drv_data); + return; + } + + /* warn ... we force this to PIO mode */ + if (printk_ratelimit()) + dev_warn(&message->spi->dev, "pump_transfers: " + "DMA disabled for transfer length %ld " + "greater than %d\n", + (long)drv_data->len, MAX_DMA_LEN); } /* Setup the transfer state based on the type of transfer */ @@ -922,7 +936,7 @@ static void pump_transfers(unsigned long data) &dma_thresh)) if (printk_ratelimit()) dev_warn(&message->spi->dev, - "pump_transfer: " + "pump_transfers: " "DMA burst size reduced to " "match bits_per_word\n"); } @@ -936,8 +950,23 @@ static void pump_transfers(unsigned long data) message->state = RUNNING_STATE; - /* Try to map dma buffer and do a dma transfer if successful */ - if ((drv_data->dma_mapped = map_dma_buffers(drv_data))) { + /* Try to map dma buffer and do a dma transfer if successful, but + * only if the length is non-zero and less than MAX_DMA_LEN. + * + * Zero-length non-descriptor DMA is illegal on PXA2xx; force use + * of PIO instead. Care is needed above because the transfer may + * have have been passed with buffers that are already dma mapped. + * A zero-length transfer in PIO mode will not try to write/read + * to/from the buffers + * + * REVISIT large transfers are exactly where we most want to be + * using DMA. If this happens much, split those transfers into + * multiple DMA segments rather than forcing PIO. + */ + drv_data->dma_mapped = 0; + if (drv_data->len > 0 && drv_data->len <= MAX_DMA_LEN) + drv_data->dma_mapped = map_dma_buffers(drv_data); + if (drv_data->dma_mapped) { /* Ensure we have the correct interrupt handler */ drv_data->transfer_handler = dma_transfer; |