linux-kernel - [PATCH 4.14 071/251] MIPS: lantiq: dma: add small delay after reset

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Message-Id: <20211124115712.716656180@linuxfoundation.org>
Date:   Wed, 24 Nov 2021 12:55:13 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Aleksander Jan Bajkowski <olek2@...pl>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 071/251] MIPS: lantiq: dma: add small delay after reset

From: Aleksander Jan Bajkowski <olek2@...pl>

[ 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@...pl>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/mips/lantiq/xway/dma.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/mips/lantiq/xway/dma.c b/arch/mips/lantiq/xway/dma.c
index 805b3a6ab2d60..ce7e033b4bb18 100644
--- a/arch/mips/lantiq/xway/dma.c
+++ b/arch/mips/lantiq/xway/dma.c
@@ -22,6 +22,7 @@
 #include <linux/export.h>
 #include <linux/spinlock.h>
 #include <linux/clk.h>
+#include <linux/delay.h>
 #include <linux/err.h>
 
 #include <lantiq_soc.h>
@@ -234,6 +235,8 @@ 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);
 
-- 
2.33.0