Commit cbfe9d56 authored Nov 08, 2023 by Marek Szyprowski Committed by sanglipeng1 May 31, 2024

i2c: s3c24xx: fix read transfers in polling mode

stable inclusion
from stable-v5.10.209
commit da60686bab6beaa718f14b9964277cd61bb74bbb
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I9U3NW

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=da60686bab6beaa718f14b9964277cd61bb74bbb



--------------------------------

[ Upstream commit 0d9cf23ed55d7ba3ab26d617a3ae507863674c8f ]

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: 117053f7 ("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>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng1 <sanglipeng1@jd.com>

parent bcee7559

drivers/i2c/busses/i2c-s3c2410.c

+11 −2

Original line number	Diff line number	Diff line
		@@ -223,8 +223,17 @@ 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;