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>
diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 32ced64..9a7c62f 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -211,7 +211,7 @@
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 @@
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 @@
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;