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author | Axel Lin <axel.lin@ingics.com> | 2015-01-06 00:08:25 (GMT) |
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committer | Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com> | 2015-01-06 10:22:27 (GMT) |
commit | 501943696ea4f4194705b7449547fd3d66c13e97 (patch) | |
tree | 2bca892c4f617a13727cfec6d6389a7e2b9e83ec /drivers/spi | |
parent | d622ac39274a949b6445f1bfd92dc1644014388b (diff) | |
download | u-boot-501943696ea4f4194705b7449547fd3d66c13e97.tar.xz |
spi: designware_spi: Fix detecting FIFO depth
Current code tries to find the highest valid fifo depth by checking the value
it wrote to DW_SPI_TXFLTR. There are a few problems in current code:
1) There is an off-by-one in dws->fifo_len setting because it assumes the latest
register write fails so the latest valid value should be fifo - 1.
2) We know the depth could be from 2 to 256 from HW spec, so it is not necessary
to test fifo == 257. In the case fifo is 257, it means the latest valid
setting is fifo = 256. So after the for loop iteration, we should check
fifo == 2 case instead of fifo == 257 if detecting the FIFO depth fails.
This patch fixes above issues.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Stefan Roese <sr@denx.de>
Reviewed-by: Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com>
Diffstat (limited to 'drivers/spi')
-rw-r--r-- | drivers/spi/designware_spi.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/spi/designware_spi.c b/drivers/spi/designware_spi.c index 98c9f03..0210667 100644 --- a/drivers/spi/designware_spi.c +++ b/drivers/spi/designware_spi.c @@ -164,13 +164,13 @@ static void spi_hw_init(struct dw_spi_priv *priv) if (!priv->fifo_len) { u32 fifo; - for (fifo = 2; fifo <= 257; fifo++) { + for (fifo = 2; fifo <= 256; fifo++) { dw_writew(priv, DW_SPI_TXFLTR, fifo); if (fifo != dw_readw(priv, DW_SPI_TXFLTR)) break; } - priv->fifo_len = (fifo == 257) ? 0 : fifo; + priv->fifo_len = (fifo == 2) ? 0 : fifo - 1; dw_writew(priv, DW_SPI_TXFLTR, 0); } debug("%s: fifo_len=%d\n", __func__, priv->fifo_len); |