From c587b6fa05106606053fc5e8e344f07cd34ace23 Mon Sep 17 00:00:00 2001 From: Feng Tang Date: Thu, 21 Jan 2010 10:41:10 +0800 Subject: [PATCH] spi/dw_spi: add a FIFO depth detection FIFO depth is configurable for each implementation of DW core, so add a depth detection for those interface drivers who don't set the fifo_len explicitly Signed-off-by: Feng Tang Acked-by: Jean-Hugues Deschenes Signed-off-by: Grant Likely --- drivers/spi/dw_spi.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/drivers/spi/dw_spi.c b/drivers/spi/dw_spi.c index f713af8309e3..d948ef4f3910 100644 --- a/drivers/spi/dw_spi.c +++ b/drivers/spi/dw_spi.c @@ -831,6 +831,22 @@ static void spi_hw_init(struct dw_spi *dws) spi_mask_intr(dws, 0xff); spi_enable_chip(dws, 1); flush(dws); + + /* + * Try to detect the FIFO depth if not set by interface driver, + * the depth could be from 2 to 256 from HW spec + */ + if (!dws->fifo_len) { + u32 fifo; + for (fifo = 2; fifo <= 257; fifo++) { + dw_writew(dws, txfltr, fifo); + if (fifo != dw_readw(dws, txfltr)) + break; + } + + dws->fifo_len = (fifo == 257) ? 0 : fifo; + dw_writew(dws, txfltr, 0); + } } int __devinit dw_spi_add_host(struct dw_spi *dws) -- 2.34.1