Patch "can: m_can: Reset coalescing during suspend/resume" has been added to the 6.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    can: m_can: Reset coalescing during suspend/resume

to the 6.10-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:
     can-m_can-reset-coalescing-during-suspend-resume.patch
and it can be found in the queue-6.10 subdirectory.

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



commit a9c0836f4d2085bc61ab66683afe65ab5af40da0
Author: Markus Schneider-Pargmann <msp@xxxxxxxxxxxx>
Date:   Mon Aug 5 20:30:41 2024 +0200

    can: m_can: Reset coalescing during suspend/resume
    
    [ Upstream commit a651261ac74298535f6d6316ebe27beceb6b17b1 ]
    
    During resume the interrupts are limited to IR_RF0N and the chip keeps
    running. In this case if coalescing is enabled and active we may miss
    waterlevel interrupts during suspend. It is safer to reset the
    coalescing by stopping the timer and adding IR_RF0N | IR_TEFN to the
    interrupts.
    
    This is a theoratical issue and probably extremely rare.
    
    Cc: Martin Hundebøll <martin@xxxxxxxxxx>
    Fixes: 4a94d7e31cf5 ("can: m_can: allow keeping the transceiver running in suspend")
    Signed-off-by: Markus Schneider-Pargmann <msp@xxxxxxxxxxxx>
    Link: https://lore.kernel.org/all/20240805183047.305630-2-msp@xxxxxxxxxxxx
    Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 205a6cb4470f..257d5bc0ae9e 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -2387,12 +2387,15 @@ int m_can_class_suspend(struct device *dev)
 		netif_device_detach(ndev);
 
 		/* leave the chip running with rx interrupt enabled if it is
-		 * used as a wake-up source.
+		 * used as a wake-up source. Coalescing needs to be reset then,
+		 * the timer is cancelled here, interrupts are done in resume.
 		 */
-		if (cdev->pm_wake_source)
+		if (cdev->pm_wake_source) {
+			hrtimer_cancel(&cdev->hrtimer);
 			m_can_write(cdev, M_CAN_IE, IR_RF0N);
-		else
+		} else {
 			m_can_stop(ndev);
+		}
 
 		m_can_clk_stop(cdev);
 	}
@@ -2422,6 +2425,13 @@ int m_can_class_resume(struct device *dev)
 			return ret;
 
 		if (cdev->pm_wake_source) {
+			/* Restore active interrupts but disable coalescing as
+			 * we may have missed important waterlevel interrupts
+			 * between suspend and resume. Timers are already
+			 * stopped in suspend. Here we enable all interrupts
+			 * again.
+			 */
+			cdev->active_interrupts |= IR_RF0N | IR_TEFN;
 			m_can_write(cdev, M_CAN_IE, cdev->active_interrupts);
 		} else {
 			ret  = m_can_start(ndev);