diff options
Diffstat (limited to 'drivers/spi/spi-bcm2835.c')
| -rw-r--r-- | drivers/spi/spi-bcm2835.c | 39 |
1 files changed, 11 insertions, 28 deletions
diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c index 35aebdfd3b4e..8aa22713c483 100644 --- a/drivers/spi/spi-bcm2835.c +++ b/drivers/spi/spi-bcm2835.c @@ -335,20 +335,6 @@ static int bcm2835_spi_transfer_one_irq(struct spi_master *master, return 1; } -/* - * DMA support - * - * this implementation has currently a few issues in so far as it does - * not work arrount limitations of the HW. - * - * the main one being that DMA transfers are limited to 16 bit - * (so 0 to 65535 bytes) by the SPI HW due to BCM2835_SPI_DLEN - * - * there may be a few more border-cases we may need to address as well - * but unfortunately this would mean splitting up the scatter-gather - * list making it slightly unpractical... - */ - /** * bcm2835_spi_transfer_prologue() - transfer first few bytes without DMA * @master: SPI master @@ -630,19 +616,6 @@ static bool bcm2835_spi_can_dma(struct spi_master *master, if (tfr->len < BCM2835_SPI_DMA_MIN_LENGTH) return false; - /* BCM2835_SPI_DLEN has defined a max transfer size as - * 16 bit, so max is 65535 - * we can revisit this by using an alternative transfer - * method - ideally this would get done without any more - * interaction... - */ - if (tfr->len > 65535) { - dev_warn_once(&spi->dev, - "transfer size of %d too big for dma-transfer\n", - tfr->len); - return false; - } - /* return OK */ return true; } @@ -707,7 +680,6 @@ static void bcm2835_dma_init(struct spi_master *master, struct device *dev) /* all went well, so set can_dma */ master->can_dma = bcm2835_spi_can_dma; - master->max_dma_len = 65535; /* limitation by BCM2835_SPI_DLEN */ /* need to do TX AND RX DMA, so we need dummy buffers */ master->flags = SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX; @@ -844,6 +816,17 @@ static int bcm2835_spi_prepare_message(struct spi_master *master, struct spi_device *spi = msg->spi; struct bcm2835_spi *bs = spi_master_get_devdata(master); u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS); + int ret; + + /* + * DMA transfers are limited to 16 bit (0 to 65535 bytes) by the SPI HW + * due to DLEN. Split up transfers (32-bit FIFO aligned) if the limit is + * exceeded. + */ + ret = spi_split_transfers_maxsize(master, msg, 65532, + GFP_KERNEL | GFP_DMA); + if (ret) + return ret; cs &= ~(BCM2835_SPI_CS_CPOL | BCM2835_SPI_CS_CPHA); |