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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Qii Wang <qii.wang@mediatek.com>,
        Wolfram Sang <wsa@kernel.org>
Subject: [PATCH 5.12 150/296] i2c: mediatek: Disable i2c start_en and clear intr_stat brfore reset
Date:   Mon, 31 May 2021 15:13:25 +0200
Message-Id: <20210531130708.915162917@linuxfoundation.org>
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From: Qii Wang <qii.wang@mediatek.com>

commit fed1bd51a504eb96caa38b4f13ab138fc169ea75 upstream.

The i2c controller driver do dma reset after transfer timeout,
but sometimes dma reset will trigger an unexpected DMA_ERR irq.
It will cause the i2c controller to continuously send interrupts
to the system and cause soft lock-up. So we need to disable i2c
start_en and clear intr_stat to stop i2c controller before dma
reset when transfer timeout.

Fixes: aafced673c06("i2c: mediatek: move dma reset before i2c reset")
Signed-off-by: Qii Wang <qii.wang@mediatek.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/i2c/busses/i2c-mt65xx.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/i2c/busses/i2c-mt65xx.c
+++ b/drivers/i2c/busses/i2c-mt65xx.c
@@ -478,6 +478,11 @@ static void mtk_i2c_clock_disable(struct
 static void mtk_i2c_init_hw(struct mtk_i2c *i2c)
 {
 	u16 control_reg;
+	u16 intr_stat_reg;
+
+	mtk_i2c_writew(i2c, I2C_CHN_CLR_FLAG, OFFSET_START);
+	intr_stat_reg = mtk_i2c_readw(i2c, OFFSET_INTR_STAT);
+	mtk_i2c_writew(i2c, intr_stat_reg, OFFSET_INTR_STAT);
 
 	if (i2c->dev_comp->apdma_sync) {
 		writel(I2C_DMA_WARM_RST, i2c->pdmabase + OFFSET_RST);