From d297933cc7fcfbaaf2d37570baac73287bf0357d Mon Sep 17 00:00:00 2001 From: Axel Lin Date: Mon, 5 Jan 2015 09:32:56 +0800 Subject: [PATCH] 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: Axel Lin Reviewed-and-tested-by: Andy Shevchenko Signed-off-by: Mark Brown Cc: stable@vger.kernel.org --- drivers/spi/spi-dw.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c index d0d5542efc06d..1a0f266c42685 100644 --- a/drivers/spi/spi-dw.c +++ b/drivers/spi/spi-dw.c @@ -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); } } -- 2.30.2