Patch "i2c: ocores: generate stop condition after timeout in polling mode" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    i2c: ocores: generate stop condition after timeout in polling mode

to the 5.4-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-ocores-generate-stop-condition-after-timeout-in-.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 16cd8aa76c3ca1874f848f19b91edbac878dd628
Author: Gregor Herburger <gregor.herburger@xxxxxxxxxxxx>
Date:   Thu Apr 13 11:37:37 2023 +0200

    i2c: ocores: generate stop condition after timeout in polling mode
    
    [ Upstream commit f8160d3b35fc94491bb0cb974dbda310ef96c0e2 ]
    
    In polling mode, no stop condition is generated after a timeout. This
    causes SCL to remain low and thereby block the bus. If this happens
    during a transfer it can cause slaves to misinterpret the subsequent
    transfer and return wrong values.
    
    To solve this, pass the ETIMEDOUT error up from ocores_process_polling()
    instead of setting STATE_ERROR directly. The caller is adjusted to call
    ocores_process_timeout() on error both in polling and in IRQ mode, which
    will set STATE_ERROR and generate a stop condition.
    
    Fixes: 69c8c0c0efa8 ("i2c: ocores: add polling interface")
    Signed-off-by: Gregor Herburger <gregor.herburger@xxxxxxxxxxxx>
    Signed-off-by: Matthias Schiffer <matthias.schiffer@xxxxxxxxxxxxxxx>
    Acked-by: Peter Korsgaard <peter@xxxxxxxxxxxxx>
    Reviewed-by: Andrew Lunn <andrew@xxxxxxx>
    Reviewed-by: Federico Vaga <federico.vaga@xxxxxxx>
    Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
index ca8b3ecfa93d1..1c3595c8a761a 100644
--- a/drivers/i2c/busses/i2c-ocores.c
+++ b/drivers/i2c/busses/i2c-ocores.c
@@ -343,18 +343,18 @@ static int ocores_poll_wait(struct ocores_i2c *i2c)
  * ocores_isr(), we just add our polling code around it.
  *
  * It can run in atomic context
+ *
+ * Return: 0 on success, -ETIMEDOUT on timeout
  */
-static void ocores_process_polling(struct ocores_i2c *i2c)
+static int ocores_process_polling(struct ocores_i2c *i2c)
 {
-	while (1) {
-		irqreturn_t ret;
-		int err;
+	irqreturn_t ret;
+	int err = 0;
 
+	while (1) {
 		err = ocores_poll_wait(i2c);
-		if (err) {
-			i2c->state = STATE_ERROR;
+		if (err)
 			break; /* timeout */
-		}
 
 		ret = ocores_isr(-1, i2c);
 		if (ret == IRQ_NONE)
@@ -365,13 +365,15 @@ static void ocores_process_polling(struct ocores_i2c *i2c)
 					break;
 		}
 	}
+
+	return err;
 }
 
 static int ocores_xfer_core(struct ocores_i2c *i2c,
 			    struct i2c_msg *msgs, int num,
 			    bool polling)
 {
-	int ret;
+	int ret = 0;
 	u8 ctrl;
 
 	ctrl = oc_getreg(i2c, OCI2C_CONTROL);
@@ -389,15 +391,16 @@ static int ocores_xfer_core(struct ocores_i2c *i2c,
 	oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START);
 
 	if (polling) {
-		ocores_process_polling(i2c);
+		ret = ocores_process_polling(i2c);
 	} else {
-		ret = wait_event_timeout(i2c->wait,
-					 (i2c->state == STATE_ERROR) ||
-					 (i2c->state == STATE_DONE), HZ);
-		if (ret == 0) {
-			ocores_process_timeout(i2c);
-			return -ETIMEDOUT;
-		}
+		if (wait_event_timeout(i2c->wait,
+				       (i2c->state == STATE_ERROR) ||
+				       (i2c->state == STATE_DONE), HZ) == 0)
+			ret = -ETIMEDOUT;
+	}
+	if (ret) {
+		ocores_process_timeout(i2c);
+		return ret;
 	}
 
 	return (i2c->state == STATE_DONE) ? num : -EIO;