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spi: imx: adjust watermark level according to transfer length 

Previously DMA watermark level is configured to fifosize/2,
DMA mode can be used only when transfer length can be divided
by 'watermark level * bpw', which makes DMA mode not pratical.

This patch adjusts watermark level to largest number (no bigger
than fifosize/2) which can divide 'tranfer length / bpw' for
each transfer.

Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Jiada Wang 2017-01-06 04:22:18 -08:00 committed by Mark Brown
parent fafd679407
commit 66459c5a50
1 changed files with 8 additions and 8 deletions
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16
drivers/spi/spi-imx.c
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@ -211,7 +211,7 @@ static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi,
struct spi_transfer *transfer)
{
struct spi_imx_data *spi_imx = spi_master_get_devdata(master);
unsigned int bpw;
unsigned int bpw, i;
if (!master->dma_rx)
return false;
@ -228,11 +228,15 @@ static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi,
if (bpw != 1 && bpw != 2 && bpw != 4)
return false;
if (transfer->len < spi_imx->wml * bpw)
for (i = spi_imx_get_fifosize(spi_imx) / 2; i > 0; i--) {
if (!(transfer->len % (i * bpw)))
break;
}
if (i == 0)
return false;
if (transfer->len % (spi_imx->wml * bpw))
return false;
spi_imx->wml = i;
return true;
}
@ -837,10 +841,6 @@ static int spi_imx_dma_configure(struct spi_master *master,
struct dma_slave_config rx = {}, tx = {};
struct spi_imx_data *spi_imx = spi_master_get_devdata(master);
if (bytes_per_word == spi_imx->bytes_per_word)
/* Same as last time */
return 0;
switch (bytes_per_word) {
case 4:
buswidth = DMA_SLAVE_BUSWIDTH_4_BYTES;