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authorAndy Shevchenko <andriy.shevchenko@linux.intel.com>2015-02-25 12:39:36 +0300
committerMark Brown <broonie@kernel.org>2015-02-26 05:09:51 +0300
commit9d239d353c319f9ff884c287ce47feb7cdf60ddc (patch)
treea30fb77d6c28bf18e6433df1db4fc4bf27d04295 /drivers/spi/spi-dw.c
parent307ed83c8c2004c9eb022e8eab326d494223e4ba (diff)
downloadlinux-9d239d353c319f9ff884c287ce47feb7cdf60ddc.tar.xz
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.c4
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);
}
}