4.18-stable review patch. If anyone has any objections, please let me know.
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From: Masahiro Yamada yamada.masahiro@socionext.com
commit cf51e4b9c34407bf0c3d9b582b7837e047e1df47 upstream.
I thought the read-back of the DMA_ENABLE register was unnecessary (at least it is working on my boards), then deleted it in commit 586a2c52909d ("mtd: nand: denali: squash denali_enable_dma() helper into caller"). Sorry, I was wrong - it caused a timing issue on Cyclone5 SoCFPGAs.
Revive the register read-back, commenting why this is necessary.
Fixes: 586a2c52909d ("mtd: nand: denali: squash denali_enable_dma() helper into caller") Cc: stable@vger.kernel.org Reported-by: Steffen Trumtrar s.trumtrar@pengutronix.de Signed-off-by: Masahiro Yamada yamada.masahiro@socionext.com Reviewed-by: Miquel Raynal miquel.raynal@bootlin.com Signed-off-by: Boris Brezillon boris.brezillon@bootlin.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/mtd/nand/raw/denali.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/drivers/mtd/nand/raw/denali.c +++ b/drivers/mtd/nand/raw/denali.c @@ -604,6 +604,12 @@ static int denali_dma_xfer(struct denali }
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);