diff options
author | Axel Lin <axel.lin@ingics.com> | 2015-01-05 09:32:56 +0800 |
---|---|---|
committer | Ben Hutchings <ben@decadent.org.uk> | 2015-02-20 00:49:33 +0000 |
commit | 250dbefd2d4437e39fef2ff3b0ee121267a5c688 (patch) | |
tree | 1348d37a3ce66e1afbe02fd3476dcfc5c1021ca4 /drivers | |
parent | 4c30f3c9a8c6e90dcb8fce6a3b718e1ddb998351 (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>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'drivers')
-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 9eddaab7b915..bbdf0cf7434b 100644 --- a/drivers/spi/spi-dw.c +++ b/drivers/spi/spi-dw.c @@ -786,13 +786,13 @@ 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); } } |