Commit d297933c authored by Axel Lin's avatar Axel Lin Committed by Mark Brown

spi: dw: Fix detecting FIFO depth

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: default avatarAxel Lin <axel.lin@ingics.com>
Reviewed-and-tested-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
parent 97bf6af1
......@@ -621,13 +621,13 @@ 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);
}
}
......
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