at_hdmac uses __raw_writel for register writes. In the absence of a barrier, the CPU may reorder the register operations. Introduce a write memory barrier so that the CPU does not reorder the channel enable, thus the start of the transfer, without making sure that all the pre-required register fields are already written.
Fixes: dc78baa2b90b ("dmaengine: at_hdmac: new driver for the Atmel AHB DMA Controller") Reported-by: Peter Rosin peda@axentia.se Cc: stable@vger.kernel.org Signed-off-by: Tudor Ambarus tudor.ambarus@microchip.com Link: https://lore.kernel.org/lkml/13c6c9a2-6db5-c3bf-349b-4c127ad3496a@axentia.se... --- drivers/dma/at_hdmac.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c index 825a29ede35e..1cb0d26d30ed 100644 --- a/drivers/dma/at_hdmac.c +++ b/drivers/dma/at_hdmac.c @@ -691,6 +691,8 @@ static void atc_dostart(struct at_dma_chan *atchan, struct at_desc *first) channel_writel(atchan, DPIP, FIELD_PREP(ATC_DPIP_HOLE, first->dst_hole) | FIELD_PREP(ATC_DPIP_BOUNDARY, first->boundary)); + /* Don't allow CPU to reorder channel enable. */ + wmb(); dma_writel(atdma, CHER, atchan->mask);
vdbg_dump_regs(atchan);