Patch "phy: lynx-28g: lock PHY while performing CDR lock workaround" has been added to the 6.5-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    phy: lynx-28g: lock PHY while performing CDR lock workaround

to the 6.5-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:
     phy-lynx-28g-lock-phy-while-performing-cdr-lock-work.patch
and it can be found in the queue-6.5 subdirectory.

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



commit 078f979664d9130f2c9afc322aa6a110df1ec677
Author: Vladimir Oltean <vladimir.oltean@xxxxxxx>
Date:   Wed Oct 4 14:17:07 2023 +0300

    phy: lynx-28g: lock PHY while performing CDR lock workaround
    
    [ Upstream commit 0ac87fe54a171d18c5fb5345e3ee8d14e1b06f4b ]
    
    lynx_28g_cdr_lock_check() runs once per second in a workqueue to reset
    the lane receiver if the CDR has not locked onto bit transitions in the
    RX stream. But the PHY consumer may do stuff with the PHY simultaneously,
    and that isn't okay. Block concurrent generic PHY calls by holding the
    PHY mutex from this workqueue.
    
    Fixes: 8f73b37cf3fb ("phy: add support for the Layerscape SerDes 28G")
    Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/phy/freescale/phy-fsl-lynx-28g.c b/drivers/phy/freescale/phy-fsl-lynx-28g.c
index 9d55dbee2e0a5..d49aa59c7d812 100644
--- a/drivers/phy/freescale/phy-fsl-lynx-28g.c
+++ b/drivers/phy/freescale/phy-fsl-lynx-28g.c
@@ -507,11 +507,12 @@ static void lynx_28g_cdr_lock_check(struct work_struct *work)
 	for (i = 0; i < LYNX_28G_NUM_LANE; i++) {
 		lane = &priv->lane[i];
 
-		if (!lane->init)
-			continue;
+		mutex_lock(&lane->phy->mutex);
 
-		if (!lane->powered_up)
+		if (!lane->init || !lane->powered_up) {
+			mutex_unlock(&lane->phy->mutex);
 			continue;
+		}
 
 		rrstctl = lynx_28g_lane_read(lane, LNaRRSTCTL);
 		if (!(rrstctl & LYNX_28G_LNaRRSTCTL_CDR_LOCK)) {
@@ -520,6 +521,8 @@ static void lynx_28g_cdr_lock_check(struct work_struct *work)
 				rrstctl = lynx_28g_lane_read(lane, LNaRRSTCTL);
 			} while (!(rrstctl & LYNX_28G_LNaRRSTCTL_RST_DONE));
 		}
+
+		mutex_unlock(&lane->phy->mutex);
 	}
 	queue_delayed_work(system_power_efficient_wq, &priv->cdr_check,
 			   msecs_to_jiffies(1000));