diff options
author | Axel Lin <axel.lin@ingics.com> | 2015-01-05 09:32:56 +0800 |
---|---|---|
committer | Zefan Li <lizefan@huawei.com> | 2015-04-14 17:33:55 +0800 |
commit | 322c22aadcd3c620d92d7032edfa6528a00d393a (patch) | |
tree | acd63a273ed3660adf4e3b2f0d0b21e676f13738 /drivers/spi | |
parent | b447eaa7d22db0fee573a6f859fba2cdfbb6d92d (diff) |
spi: dw: Fix detecting FIFO depth
commit d297933cc7fcfbaaf2d37570baac73287bf0357d upstream.
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>
Reviewed-and-tested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@huawei.com>
Diffstat (limited to 'drivers/spi')
-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 ff06b428b1e4..71ef1e487a91 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 <= 257; fifo++) { + for (fifo = 2; fifo <= 256; fifo++) { dw_writew(dws, DW_SPI_TXFLTR, fifo); if (fifo != dw_readw(dws, DW_SPI_TXFLTR)) break; } - dws->fifo_len = (fifo == 257) ? 0 : fifo; + dws->fifo_len = (fifo == 2) ? 0 : fifo - 1; dw_writew(dws, DW_SPI_TXFLTR, 0); } } |