From: Martin Sperl <[email protected]> Moved to the new spi_transfer transformation methods to work arround the HW restrictions in place arround DMA and alignment or max_length.
Signed-off-by: Martin Sperl <[email protected]> --- drivers/spi/spi-bcm2835.c | 53 ++++++++++++++++++--------------------------- 1 file changed, 21 insertions(+), 32 deletions(-) diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c index cf04960..67516f7 100644 --- a/drivers/spi/spi-bcm2835.c +++ b/drivers/spi/spi-bcm2835.c @@ -365,38 +365,6 @@ 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; - } - - /* if we run rx/tx_buf with word aligned addresses then we are OK */ - if ((((size_t)tfr->rx_buf & 3) == 0) && - (((size_t)tfr->tx_buf & 3) == 0)) - return true; - - /* otherwise we only allow transfers within the same page - * to avoid wasting time on dma_mapping when it is not practical - */ - if (((size_t)tfr->tx_buf & (PAGE_SIZE - 1)) + tfr->len > PAGE_SIZE) { - dev_warn_once(&spi->dev, - "Unaligned spi tx-transfer bridging page\n"); - return false; - } - if (((size_t)tfr->rx_buf & (PAGE_SIZE - 1)) + tfr->len > PAGE_SIZE) { - dev_warn_once(&spi->dev, - "Unaligned spi rx-transfer bridging page\n"); - return false; - } - /* return OK */ return true; } @@ -598,8 +566,28 @@ 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; + + /* apply some spi_transfer transformations */ + + /* align transfers on words length - avoiding + * that the scatter/gather list produces transfers + * that are not a multiple of 4 + */ + ret = spi_split_transfers_first_page_len_not_aligned( + master, msg, true, 4); + if (ret) + return ret; + + /* limit the max transfer size to 15 * PAGE_SIZE + * the bcm2835 HW limit is actually 65535, but to avoid + * another set of alignment issues we limit ourselves + */ + ret = spi_split_transfers_maxsize(master, msg, 15 * PAGE_SIZE); + if (ret) + return ret; + /* setting up clock and data polarity prior to asserting GPIO-cs */ cs &= ~(BCM2835_SPI_CS_CPOL | BCM2835_SPI_CS_CPHA); if (spi->mode & SPI_CPOL) -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
