From 9d43649a7740cf715c750929d19661a35144e7d1 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Wed, 19 Dec 2018 20:03:19 +0900 Subject: [PATCH] mtd: rawnand: denali: fix a race condition when DMA is kicked Based on Linux commit cf51e4b9c34407bf0c3d9b582b7837e047e1df47 Add the register read-back, commenting why this is necessary. Signed-off-by: Masahiro Yamada --- drivers/mtd/nand/raw/denali.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/mtd/nand/raw/denali.c b/drivers/mtd/nand/raw/denali.c index bbfa3b6112..e0eb1339ec 100644 --- a/drivers/mtd/nand/raw/denali.c +++ b/drivers/mtd/nand/raw/denali.c @@ -587,6 +587,12 @@ static int denali_dma_xfer(struct denali_nand_info *denali, void *buf, } iowrite32(DMA_ENABLE__FLAG, denali->reg + DMA_ENABLE); + /* + * The ->setup_dma() hook kicks DMA by using the data/command + * interface, which belongs to a different AXI port from the + * register interface. Read back the register to avoid a race. + */ + ioread32(denali->reg + DMA_ENABLE); denali_reset_irq(denali); denali->setup_dma(denali, dma_addr, page, write); -- 2.25.1