From: Alexander Stein <alexander.stein@ew.tq-group.com>
Date: Mon, 30 Jan 2023 16:32:47 +0100
Subject: [PATCH] i2c: imx-lpi2c: check only for enabled interrupt flags
References: bsc#1012628
Patch-mainline: 6.2.9
Git-commit: 1c7885004567e8951d65a983be095f254dd20bef

[ Upstream commit 1c7885004567e8951d65a983be095f254dd20bef ]

When reading from I2C, the Tx watermark is set to 0. Unfortunately the
TDF (transmit data flag) is enabled when Tx FIFO entries is equal or less
than watermark. So it is set in every case, hence the reset default of 1.
This results in the MSR_RDF _and_ MSR_TDF flags to be set thus trying
to send Tx data on a read message.
Mask the IRQ status to filter for wanted flags only.

Fixes: a55fa9d0e42e ("i2c: imx-lpi2c: add low power i2c bus driver")
Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Tested-by: Emanuele Ghidoli <emanuele.ghidoli@toradex.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/i2c/busses/i2c-imx-lpi2c.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c b/drivers/i2c/busses/i2c-imx-lpi2c.c
index 188f2a36..9b2f9544 100644
--- a/drivers/i2c/busses/i2c-imx-lpi2c.c
+++ b/drivers/i2c/busses/i2c-imx-lpi2c.c
@@ -503,10 +503,14 @@ static int lpi2c_imx_xfer(struct i2c_adapter *adapter,
 static irqreturn_t lpi2c_imx_isr(int irq, void *dev_id)
 {
 	struct lpi2c_imx_struct *lpi2c_imx = dev_id;
+	unsigned int enabled;
 	unsigned int temp;
 
+	enabled = readl(lpi2c_imx->base + LPI2C_MIER);
+
 	lpi2c_imx_intctrl(lpi2c_imx, 0);
 	temp = readl(lpi2c_imx->base + LPI2C_MSR);
+	temp &= enabled;
 
 	if (temp & MSR_RDF)
 		lpi2c_imx_read_rxfifo(lpi2c_imx);
-- 
2.35.3