This is a note to let you know that I've just added the patch titled
MIPS: lantiq: dma: add small delay after reset
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mips-lantiq-dma-add-small-delay-after-reset.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 91e9170242290a678083a53fd88510b1833336bf
Author: Aleksander Jan Bajkowski <olek2@xxxxx>
Date: Tue Sep 14 23:20:58 2021 +0200
MIPS: lantiq: dma: add small delay after reset
[ Upstream commit c12aa581f6d5e80c3c3675ab26a52c2b3b62f76e ]
Reading the DMA registers immediately after the reset causes
Data Bus Error. Adding a small delay fixes this issue.
Signed-off-by: Aleksander Jan Bajkowski <olek2@xxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/mips/lantiq/xway/dma.c b/arch/mips/lantiq/xway/dma.c
index aeb1b989cd4ee..24c6267f78698 100644
--- a/arch/mips/lantiq/xway/dma.c
+++ b/arch/mips/lantiq/xway/dma.c
@@ -11,6 +11,7 @@
#include <linux/export.h>
#include <linux/spinlock.h>
#include <linux/clk.h>
+#include <linux/delay.h>
#include <linux/err.h>
#include <lantiq_soc.h>
@@ -221,6 +222,8 @@ ltq_dma_init(struct platform_device *pdev)
clk_enable(clk);
ltq_dma_w32_mask(0, DMA_RESET, LTQ_DMA_CTRL);
+ usleep_range(1, 10);
+
/* disable all interrupts */
ltq_dma_w32(0, LTQ_DMA_IRNEN);
