diff options
author | Andy Shevchenko <andriy.shevchenko@linux.intel.com> | 2015-02-25 11:39:36 +0200 |
---|---|---|
committer | Zefan Li <lizefan@huawei.com> | 2015-04-14 17:34:04 +0800 |
commit | 8b19cfea81e37f215399a3d5481f899ba24f30c5 (patch) | |
tree | 7178169d661187a33ae4f4d9db04be395a105d4b | |
parent | f8cce9e338db5d455e62a4b9abbbeda3d5a0e203 (diff) |
spi: dw: revisit FIFO size detection again
commit 9d239d353c319f9ff884c287ce47feb7cdf60ddc upstream.
The commit d297933cc7fc (spi: dw: Fix detecting FIFO depth) tries to fix the
logic of the FIFO detection based on the description on the comments. However,
there is a slight difference between numbers in TX Level and TX FIFO size.
So, by specification the FIFO size would be in a range 2-256 bytes. From TX
Level prospective it means we can set threshold in the range 0-(FIFO size - 1)
bytes. Hence there are currently two issues:
a) FIFO size 2 bytes is actually skipped since TX Level is 1 bit and could be
either 0 or 1 byte;
b) FIFO size is incorrectly decreased by 1 which already done by meaning of
TX Level register.
This patch fixes it eventually right.
Fixes: d297933cc7fc (spi: dw: Fix detecting FIFO depth)
Reviewed-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Zefan Li <lizefan@huawei.com>
-rw-r--r-- | drivers/spi/spi-dw.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c index 71ef1e487a91..cce2d7b90aad 100644 --- a/drivers/spi/spi-dw.c +++ b/drivers/spi/spi-dw.c @@ -780,13 +780,13 @@ static void spi_hw_init(struct dw_spi *dws) */ if (!dws->fifo_len) { u32 fifo; - for (fifo = 2; fifo <= 256; fifo++) { + for (fifo = 1; fifo < 256; fifo++) { dw_writew(dws, DW_SPI_TXFLTR, fifo); if (fifo != dw_readw(dws, DW_SPI_TXFLTR)) break; } - dws->fifo_len = (fifo == 2) ? 0 : fifo - 1; + dws->fifo_len = (fifo == 1) ? 0 : fifo; dw_writew(dws, DW_SPI_TXFLTR, 0); } } |