4.19-stable review patch. If anyone has any objections, please let me know.
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From: Marek Szyprowski m.szyprowski@samsung.com
[ 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: 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 Signed-off-by: Wolfram Sang wsa@kernel.org Signed-off-by: Sasha Levin sashal@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 4c6036920388..8186af573a02 100644 --- a/drivers/i2c/busses/i2c-s3c2410.c +++ b/drivers/i2c/busses/i2c-s3c2410.c @@ -233,8 +233,17 @@ 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;