Patch "soundwire: intel_bus_common: enable interrupts before exiting reset" has been added to the 6.11-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    soundwire: intel_bus_common: enable interrupts before exiting reset

to the 6.11-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:
     soundwire-intel_bus_common-enable-interrupts-before-.patch
and it can be found in the queue-6.11 subdirectory.

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



commit b40182e245164262f9598d4745654df19d891f24
Author: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxx>
Date:   Mon Aug 5 19:50:03 2024 +0800

    soundwire: intel_bus_common: enable interrupts before exiting reset
    
    [ Upstream commit 5aedb8d8336b0a0421b58ca27d1b572aa6695b5b ]
    
    The existing code enables the Cadence IP interrupts after the bus
    reset sequence. The problem with this sequence is that it might be
    pre-empted, giving SoundWire devices time to sync and report as
    ATTACHED before the interrupts are enabled. In that case, the Cadence
    IP will not detect a state change and will not throw an interrupt to
    proceed with the enumeration of a Device0.
    
    In our overnight stress tests, we observed that a slight
    sub-millisecond delay in enabling interrupts after the reset was
    correlated with detection failures. This problem is more prevalent on
    the LunarLake silicon, likely due to SOC integration changes, but it
    was observed on earlier generations as well.
    
    This patch reverts the sequence, with the interrupts enabled before
    performing the bus reset. This removes the race condition and makes
    sure the Cadence IP is able to detect the presence of a Device0 in all
    cases.
    
    Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
    Signed-off-by: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20240805115003.88035-1-yung-chuan.liao@xxxxxxxxxxxxxxx
    Signed-off-by: Vinod Koul <vkoul@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/soundwire/intel_bus_common.c b/drivers/soundwire/intel_bus_common.c
index df944e11b9caa..a75e5d7d87154 100644
--- a/drivers/soundwire/intel_bus_common.c
+++ b/drivers/soundwire/intel_bus_common.c
@@ -45,15 +45,15 @@ int intel_start_bus(struct sdw_intel *sdw)
 		return ret;
 	}
 
-	ret = sdw_cdns_exit_reset(cdns);
+	ret = sdw_cdns_enable_interrupt(cdns, true);
 	if (ret < 0) {
-		dev_err(dev, "%s: unable to exit bus reset sequence: %d\n", __func__, ret);
+		dev_err(dev, "%s: cannot enable interrupts: %d\n", __func__, ret);
 		return ret;
 	}
 
-	ret = sdw_cdns_enable_interrupt(cdns, true);
+	ret = sdw_cdns_exit_reset(cdns);
 	if (ret < 0) {
-		dev_err(dev, "%s: cannot enable interrupts: %d\n", __func__, ret);
+		dev_err(dev, "%s: unable to exit bus reset sequence: %d\n", __func__, ret);
 		return ret;
 	}
 
@@ -136,15 +136,15 @@ int intel_start_bus_after_reset(struct sdw_intel *sdw)
 			return ret;
 		}
 
-		ret = sdw_cdns_exit_reset(cdns);
+		ret = sdw_cdns_enable_interrupt(cdns, true);
 		if (ret < 0) {
-			dev_err(dev, "unable to exit bus reset sequence during resume\n");
+			dev_err(dev, "cannot enable interrupts during resume\n");
 			return ret;
 		}
 
-		ret = sdw_cdns_enable_interrupt(cdns, true);
+		ret = sdw_cdns_exit_reset(cdns);
 		if (ret < 0) {
-			dev_err(dev, "cannot enable interrupts during resume\n");
+			dev_err(dev, "unable to exit bus reset sequence during resume\n");
 			return ret;
 		}