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author | 2015-02-25 11:39:36 +0200 | |
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committer | 2015-02-26 11:09:51 +0900 | |
commit | 9d239d353c319f9ff884c287ce47feb7cdf60ddc (patch) | |
tree | a30fb77d6c28bf18e6433df1db4fc4bf27d04295 /drivers/spi/spi-dw.c | |
parent | spi: dw-pci: correct number of chip selects (diff) | |
download | linux-9d239d353c319f9ff884c287ce47feb7cdf60ddc.tar.gz linux-9d239d353c319f9ff884c287ce47feb7cdf60ddc.tar.bz2 linux-9d239d353c319f9ff884c287ce47feb7cdf60ddc.zip |
spi: dw: revisit FIFO size detection again
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>
Cc: stable@vger.kernel.org
Diffstat (limited to 'drivers/spi/spi-dw.c')
-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 5a97a62b298a..4847afba89f4 100644 --- a/drivers/spi/spi-dw.c +++ b/drivers/spi/spi-dw.c @@ -621,14 +621,14 @@ static void spi_hw_init(struct device *dev, 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; } dw_writew(dws, DW_SPI_TXFLTR, 0); - dws->fifo_len = (fifo == 2) ? 0 : fifo - 1; + dws->fifo_len = (fifo == 1) ? 0 : fifo; dev_dbg(dev, "Detected FIFO size: %u bytes\n", dws->fifo_len); } } |