[PATCH v4 1/3] i2c: s3c24xx: fix read transfers in polling mode

[Marek Szyprowski <m.szyprowski@samsung.com>]

To properly handle read transfers in polling mode, no waiting for the ACK
state is needed as it will never come. Just wait a bit to ensure start
state is on the bus and continue processing next bytes.

Fixes: 117053f77a5a ("i2c: s3c2410: Add polling mode support")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Chanho Park <chanho61.park@samsung.com>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
---
 drivers/i2c/busses/i2c-s3c2410.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
index c56886af724e..bf9a5670ef33 100644
--- a/drivers/i2c/busses/i2c-s3c2410.c
+++ b/drivers/i2c/busses/i2c-s3c2410.c
@@ -216,8 +216,17 @@ static bool is_ack(struct s3c24xx_i2c *i2c)
 	int tries;
 
 	for (tries = 50; tries; --tries) {
-		if (readl(i2c->regs + S3C2410_IICCON)
-			& S3C2410_IICCON_IRQPEND) {
+		unsigned long tmp = readl(i2c->regs + S3C2410_IICCON);
+
+		if (!(tmp & S3C2410_IICCON_ACKEN)) {
+			/*
+			 * Wait a bit for the bus to stabilize,
+			 * delay estimated experimentally.
+			 */
+			usleep_range(100, 200);
+			return true;
+		}
+		if (tmp & S3C2410_IICCON_IRQPEND) {
 			if (!(readl(i2c->regs + S3C2410_IICSTAT)
 				& S3C2410_IICSTAT_LASTBIT))
 				return true;
-- 
2.34.1