This is a note to let you know that I've just added the patch titled
i2c: s3c24xx: fix read transfers in polling mode
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
i2c-s3c24xx-fix-read-transfers-in-polling-mode.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 800ab8201ac06f6c51cd501e16469921f40b72b3
Author: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Date: Wed Nov 8 17:43:52 2023 +0100
i2c: s3c24xx: fix read transfers in polling mode
[ 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@xxxxxxxxxxx>
Reviewed-by: Chanho Park <chanho61.park@xxxxxxxxxxx>
Reviewed-by: Andi Shyti <andi.shyti@xxxxxxxxxx>
Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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;
