The upper limit for DMA transfer length on MX28 is 0x4000 bytes, otherwise the DMA refuses to operate.
Signed-off-by: Marek Vasut marex@denx.de Cc: Fabio Estevam festevam@gmail.com Cc: Otavio Salvador otavio@ossystems.com.br Cc: Stefano Babic sbabic@denx.de --- drivers/spi/mxs_spi.c | 31 ++++++++++++++++++++++--------- 1 file changed, 22 insertions(+), 9 deletions(-)
diff --git a/drivers/spi/mxs_spi.c b/drivers/spi/mxs_spi.c index a037c13..fb6a167 100644 --- a/drivers/spi/mxs_spi.c +++ b/drivers/spi/mxs_spi.c @@ -287,9 +287,9 @@ static int mxs_spi_xfer_dma(struct mxs_spi_slave *slave, int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout, void *din, unsigned long flags) { - struct mxs_spi_slave *mxs_slave = to_mxs_slave(slave); - struct mxs_ssp_regs *ssp_regs = mxs_slave->regs; - int len = bitlen / 8; + struct mxs_spi_slave *sslave = to_mxs_slave(slave); + struct mxs_ssp_regs *regs = sslave->regs; + int len = bitlen / 8, tl, ret; char dummy; int write = 0; char *data = NULL; @@ -335,11 +335,24 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen, dma = 0; }
- if (!dma || (len < MXSSSP_SMALL_TRANSFER)) { - writel(SSP_CTRL1_DMA_ENABLE, &ssp_regs->hw_ssp_ctrl1_clr); - return mxs_spi_xfer_pio(mxs_slave, data, len, write, flags); - } else { - writel(SSP_CTRL1_DMA_ENABLE, &ssp_regs->hw_ssp_ctrl1_set); - return mxs_spi_xfer_dma(mxs_slave, data, len, write, flags); + while (len) { + if (!dma || (len < MXSSSP_SMALL_TRANSFER)) { + tl = len; + writel(SSP_CTRL1_DMA_ENABLE, ®s->hw_ssp_ctrl1_clr); + ret = mxs_spi_xfer_pio(sslave, data, tl, write, flags); + } else { + /* 0x4000 bytes is the limit for DMA burst. */ + tl = min(len, 0x4000); + writel(SSP_CTRL1_DMA_ENABLE, ®s->hw_ssp_ctrl1_set); + ret = mxs_spi_xfer_dma(sslave, data, tl, write, flags); + } + + if (ret) + return ret; + + data += tl; + len -= tl; } + + return ret; }