Patch "i2c: xiic: Defer xiic_wakeup() and __xiic_start_xfer() in xiic_process()" 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: xiic: Defer xiic_wakeup() and __xiic_start_xfer() in xiic_process()

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-xiic-defer-xiic_wakeup-and-__xiic_start_xfer-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 55e0d2495f220a9481e73f0e53e8223c51ae11e2
Author: Marek Vasut <marex@xxxxxxx>
Date:   Mon Aug 23 23:41:42 2021 +0200

    i2c: xiic: Defer xiic_wakeup() and __xiic_start_xfer() in xiic_process()
    
    [ Upstream commit 743e227a895923c37a333eb2ebf3e391f00c406d ]
    
    The __xiic_start_xfer() manipulates the interrupt flags, xiic_wakeup()
    may result in return from xiic_xfer() early. Defer both to the end of
    the xiic_process() interrupt thread, so that they are executed after
    all the other interrupt bits handling completed and once it completely
    safe to perform changes to the interrupt bits in the hardware.
    
    Signed-off-by: Marek Vasut <marex@xxxxxxx>
    Acked-by: Michal Simek <michal.simek@xxxxxxxxxx>
    Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxx>
    Stable-dep-of: cb6e45c9a0ad ("i2c: xiic: Don't try to handle more interrupt events after error")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/i2c/busses/i2c-xiic.c b/drivers/i2c/busses/i2c-xiic.c
index c92ea6990ec69..c3fcaf5decc74 100644
--- a/drivers/i2c/busses/i2c-xiic.c
+++ b/drivers/i2c/busses/i2c-xiic.c
@@ -353,6 +353,9 @@ static irqreturn_t xiic_process(int irq, void *dev_id)
 	struct xiic_i2c *i2c = dev_id;
 	u32 pend, isr, ier;
 	u32 clr = 0;
+	int xfer_more = 0;
+	int wakeup_req = 0;
+	int wakeup_code = 0;
 
 	/* Get the interrupt Status from the IPIF. There is no clearing of
 	 * interrupts in the IPIF. Interrupts must be cleared at the source.
@@ -389,10 +392,14 @@ static irqreturn_t xiic_process(int irq, void *dev_id)
 		 */
 		xiic_reinit(i2c);
 
-		if (i2c->rx_msg)
-			xiic_wakeup(i2c, STATE_ERROR);
-		if (i2c->tx_msg)
-			xiic_wakeup(i2c, STATE_ERROR);
+		if (i2c->rx_msg) {
+			wakeup_req = 1;
+			wakeup_code = STATE_ERROR;
+		}
+		if (i2c->tx_msg) {
+			wakeup_req = 1;
+			wakeup_code = STATE_ERROR;
+		}
 	}
 	if (pend & XIIC_INTR_RX_FULL_MASK) {
 		/* Receive register/FIFO is full */
@@ -426,8 +433,7 @@ static irqreturn_t xiic_process(int irq, void *dev_id)
 				i2c->tx_msg++;
 				dev_dbg(i2c->adap.dev.parent,
 					"%s will start next...\n", __func__);
-
-				__xiic_start_xfer(i2c);
+				xfer_more = 1;
 			}
 		}
 	}
@@ -441,11 +447,13 @@ static irqreturn_t xiic_process(int irq, void *dev_id)
 		if (!i2c->tx_msg)
 			goto out;
 
-		if ((i2c->nmsgs == 1) && !i2c->rx_msg &&
-			xiic_tx_space(i2c) == 0)
-			xiic_wakeup(i2c, STATE_DONE);
+		wakeup_req = 1;
+
+		if (i2c->nmsgs == 1 && !i2c->rx_msg &&
+		    xiic_tx_space(i2c) == 0)
+			wakeup_code = STATE_DONE;
 		else
-			xiic_wakeup(i2c, STATE_ERROR);
+			wakeup_code = STATE_ERROR;
 	}
 	if (pend & (XIIC_INTR_TX_EMPTY_MASK | XIIC_INTR_TX_HALF_MASK)) {
 		/* Transmit register/FIFO is empty or ½ empty */
@@ -469,7 +477,7 @@ static irqreturn_t xiic_process(int irq, void *dev_id)
 			if (i2c->nmsgs > 1) {
 				i2c->nmsgs--;
 				i2c->tx_msg++;
-				__xiic_start_xfer(i2c);
+				xfer_more = 1;
 			} else {
 				xiic_irq_dis(i2c, XIIC_INTR_TX_HALF_MASK);
 
@@ -487,6 +495,13 @@ static irqreturn_t xiic_process(int irq, void *dev_id)
 	dev_dbg(i2c->adap.dev.parent, "%s clr: 0x%x\n", __func__, clr);
 
 	xiic_setreg32(i2c, XIIC_IISR_OFFSET, clr);
+	if (xfer_more)
+		__xiic_start_xfer(i2c);
+	if (wakeup_req)
+		xiic_wakeup(i2c, wakeup_code);
+
+	WARN_ON(xfer_more && wakeup_req);
+
 	mutex_unlock(&i2c->lock);
 	return IRQ_HANDLED;
 }