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authorTudor Ambarus <tudor.ambarus@microchip.com>2022-10-25 12:02:47 +0300
committerVinod Koul <vkoul@kernel.org>2022-11-08 10:43:57 +0530
commit580ee84405c27d6ed419abe4d2b3de1968abdafd (patch)
tree2a9ed9d6c292a6a4a3a20289544fd1f595714504 /drivers/dma/at_hdmac.c
parentef2cb4f0ce479f77607b04c4b0414bf32f863ee8 (diff)
dmaengine: at_hdmac: Don't allow CPU to reorder channel enable
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> Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/lkml/13c6c9a2-6db5-c3bf-349b-4c127ad3496a@axentia.se/ Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com> Link: https://lore.kernel.org/r/20221025090306.297886-1-tudor.ambarus@microchip.com Link: https://lore.kernel.org/r/20221025090306.297886-14-tudor.ambarus@microchip.com Signed-off-by: Vinod Koul <vkoul@kernel.org>
Diffstat (limited to 'drivers/dma/at_hdmac.c')
-rw-r--r--drivers/dma/at_hdmac.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 80eeb4fb88ef..968a5aba47cd 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -256,6 +256,8 @@ static void atc_dostart(struct at_dma_chan *atchan, struct at_desc *first)
ATC_SPIP_BOUNDARY(first->boundary));
channel_writel(atchan, DPIP, ATC_DPIP_HOLE(first->dst_hole) |
ATC_DPIP_BOUNDARY(first->boundary));
+ /* Don't allow CPU to reorder channel enable. */
+ wmb();
dma_writel(atdma, CHER, atchan->mask);
vdbg_dump_regs(atchan);