From: Reid Tonking <reidt@ti.com>
Date: Wed, 26 Apr 2023 14:49:56 -0500
Subject: [PATCH] i2c: omap: Fix standard mode false ACK readings
References: bsc#1012628
Patch-mainline: 6.3.2
Git-commit: c770657bd2611b077ec1e7b1fe6aa92f249399bd

commit c770657bd2611b077ec1e7b1fe6aa92f249399bd upstream.

Using standard mode, rare false ACK responses were appearing with
i2cdetect tool. This was happening due to NACK interrupt triggering
ISR thread before register access interrupt was ready. Removing the
NACK interrupt's ability to trigger ISR thread lets register access
ready interrupt do this instead.

Cc: <stable@vger.kernel.org> # v3.7+
Fixes: 3b2f8f82dad7 ("i2c: omap: switch to threaded IRQ support")
Signed-off-by: Reid Tonking <reidt@ti.com>
Acked-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/i2c/busses/i2c-omap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index f9ae520a..7ec25219 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -1058,7 +1058,7 @@ omap_i2c_isr(int irq, void *dev_id)
 	u16 stat;
 
 	stat = omap_i2c_read_reg(omap, OMAP_I2C_STAT_REG);
-	mask = omap_i2c_read_reg(omap, OMAP_I2C_IE_REG);
+	mask = omap_i2c_read_reg(omap, OMAP_I2C_IE_REG) & ~OMAP_I2C_STAT_NACK;
 
 	if (stat & mask)
 		ret = IRQ_WAKE_THREAD;
-- 
2.35.3