releases/5.10.209/i2c-s3c24xx-fix-transferring-more-than-one-message-i.patch

From e3510d8129503363b646891d84026f6d62860f28 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Wed, 8 Nov 2023 17:43:53 +0100
Subject: i2c: s3c24xx: fix transferring more than one message in polling mode

From: Marek Szyprowski <m.szyprowski@samsung.com>

[ Upstream commit 990489e1042c6c5d6bccf56deca68f8dbeed8180 ]

To properly handle ACK on the bus when transferring more than one
message in polling mode, move the polling handling loop from
s3c24xx_i2c_message_start() to s3c24xx_i2c_doxfer(). This way
i2c_s3c_irq_nextbyte() is always executed till the end, properly
acknowledging the IRQ bits and no recursive calls to
i2c_s3c_irq_nextbyte() are made.

While touching this, also fix finishing transfers in polling mode by
using common code path and always waiting for the bus to become idle
and disabled.

Fixes: 117053f77a5a ("i2c: s3c2410: Add polling mode support")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/i2c/busses/i2c-s3c2410.c | 27 ++++++++++-----------------
 1 file changed, 10 insertions(+), 17 deletions(-)

diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
index 687588834fc8..fd0969cd7dc6 100644
--- a/drivers/i2c/busses/i2c-s3c2410.c
+++ b/drivers/i2c/busses/i2c-s3c2410.c
@@ -286,16 +286,6 @@ static void s3c24xx_i2c_message_start(struct s3c24xx_i2c *i2c,
 
 	stat |= S3C2410_IICSTAT_START;
 	writel(stat, i2c->regs + S3C2410_IICSTAT);
-
-	if (i2c->quirks & QUIRK_POLL) {
-		while ((i2c->msg_num != 0) && is_ack(i2c)) {
-			i2c_s3c_irq_nextbyte(i2c, stat);
-			stat = readl(i2c->regs + S3C2410_IICSTAT);
-
-			if (stat & S3C2410_IICSTAT_ARBITR)
-				dev_err(i2c->dev, "deal with arbitration loss\n");
-		}
-	}
 }
 
 static inline void s3c24xx_i2c_stop(struct s3c24xx_i2c *i2c, int ret)
@@ -702,7 +692,7 @@ static void s3c24xx_i2c_wait_idle(struct s3c24xx_i2c *i2c)
 static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c,
 			      struct i2c_msg *msgs, int num)
 {
-	unsigned long timeout;
+	unsigned long timeout = 0;
 	int ret;
 
 	ret = s3c24xx_i2c_set_master(i2c);
@@ -722,16 +712,19 @@ static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c,
 	s3c24xx_i2c_message_start(i2c, msgs);
 
 	if (i2c->quirks & QUIRK_POLL) {
-		ret = i2c->msg_idx;
+		while ((i2c->msg_num != 0) && is_ack(i2c)) {
+			unsigned long stat = readl(i2c->regs + S3C2410_IICSTAT);
 
-		if (ret != num)
-			dev_dbg(i2c->dev, "incomplete xfer (%d)\n", ret);
+			i2c_s3c_irq_nextbyte(i2c, stat);
 
-		goto out;
+			stat = readl(i2c->regs + S3C2410_IICSTAT);
+			if (stat & S3C2410_IICSTAT_ARBITR)
+				dev_err(i2c->dev, "deal with arbitration loss\n");
+		}
+	} else {
+		timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);
 	}
 
-	timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);
-
 	ret = i2c->msg_idx;
 
 	/*
-- 
2.43.0