Meghana Madhyastha <meghana.madhyas...@gmail.com> writes:
> Split spi messages into chunks of <65535 in the spi subsystem and remove the
> message
> length warning in bcm2835_spi_can_dma. This is so that the messages can be
> transferred
> via dma and that the tinydrm drivers need not split it. The current chunk
> size is 65532.
> This is because the scatter gather segment is required to be multiple of 4.
> The size
> has to be <65535 due to hardware limitations.
>
> Signed-off-by: Meghana Madhyastha <meghana.madhyas...@gmail.com>
> ---
> drivers/spi/spi-bcm2835.c | 22 ++++++++--------------
> 1 file changed, 8 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
> index f35cc10772f6..280ffa5aef7e 100644
> --- a/drivers/spi/spi-bcm2835.c
> +++ b/drivers/spi/spi-bcm2835.c
> @@ -365,19 +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))
> @@ -461,7 +448,7 @@ 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 */
> + master->max_dma_len = 65532; /* 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;
>
> @@ -597,7 +584,14 @@ 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);
> + gfp_t gfp_flags = GFP_KERNEL | GFP_DMA;
> u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
> + size_t max_transfer_size = 65532;
> + int ret;
> +
> + ret = spi_split_transfers_maxsize(master, msg, max_transfer_size,
> gfp_flags);
> + if (ret)
> + return ret;Mark: is this how spi_split_transfers_maxsize() is supposed to be used? If so, I'm happy to see our hardware have fewer limitations, and it gets my: Reviewed-by: Eric Anholt <e...@anholt.net>
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