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bus: mhi: Address MHI system suspend abort

PATCH New Len Brown 2 participants 4 messages Nov 13 MHI bus

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Len Brown

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#0 lore raw

cover bus: mhi: Address MHI system suspend abort

For Upstream:

[PATCH 1/2] bus: mhi: pci_generic: Prevent MHI from aborting system suspend

For Debug of underlying MHI issue:

[RFC 2/2] bus: mhi: host: Add diagnostic print for -EBUSY in mhi_pm_suspend()

thanks,
-Len

author
#1 lore raw

PATCH v2 1/2 bus: mhi: pci_generic: Prevent MHI from aborting system suspend

From: Len Brown <[email protected]>

mhi sometimes aborts system suspend on the thinkpad T16 gen3:

mhi-pci-generic 0000:08:00.0:
... failed to suspend device: -16
... PM: pci_pm_suspend(): mhi_pci_suspend [mhi_pci_generic] returns -16 ... PM: dpm_run_callback(): pci_pm_suspend returns -16
... PM: pci_pm_suspend returned -16 after 15145 usecs
... PM: failed to suspend async: error -16

Prevent MHI from spreading this device-specific failure to the rest of the system. I.e. "Why is a modem that I don't use preventing me from suspending my laptop?"

This change does not comprehend the internal root cause of the mhi failure, which should be found and fixed.

There is also a risk that ignoring the MHI error and continuing to put the device into PCI D3 will leave it in an error state.

Fixes d3800c1dce24 ("bus: mhi: pci_generic: Add support for runtime PM")
Signed-off-by Len Brown <[email protected]>
---
 drivers/bus/mhi/host/pci_generic.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
drivers/bus/mhi/host/pci_generic.c +6 -1
index 7193a384cca4..343d1046a25e 100644
@@ -1727,7 +1727,12 @@ static int __maybe_unused mhi_pci_runtime_resume(struct device *dev)
 static int  __maybe_unused mhi_pci_suspend(struct device *dev)
 {
 	pm_runtime_disable(dev);
-	return mhi_pci_runtime_suspend(dev);
+
+	/* Ignore errors (e.g. -EBUSY); a failed modem suspend must not abort system suspend */
+	mhi_pci_runtime_suspend(dev);
+
+	/* Must return 0 to allow system suspend to continue */
+	return 0;
 }
 
 static int __maybe_unused mhi_pci_resume(struct device *dev)
Signature · 1 line
2.45.2
author
#2 lore raw

RFC 2/2 bus: mhi: host: Add diagnostic print for -EBUSY in mhi_pm_suspend()

From: Len Brown <[email protected]>

mhi_pm_suspend() sometimes returns -EBUSY, but doesn't tell us why.

Print dev_wake and pending_pkts when it does.

Signed-off-by Len Brown <[email protected]>
---
 drivers/bus/mhi/host/pm.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)
drivers/bus/mhi/host/pm.c +8 -1
index ced83fbb1a51..2eb7344b3b39 100644
@@ -871,8 +871,12 @@ int mhi_pm_suspend(struct mhi_controller *mhi_cntrl)
 
 	/* Return busy if there are any pending resources */
 	if (atomic_read(&mhi_cntrl->dev_wake) ||
-	    atomic_read(&mhi_cntrl->pending_pkts))
+	    atomic_read(&mhi_cntrl->pending_pkts)) {
+		dev_err(dev, "DEBUG: suspend busy (early): dev_wake: %d pending_pkts: %d\n",
+			atomic_read(&mhi_cntrl->dev_wake),
+			atomic_read(&mhi_cntrl->pending_pkts));
 		return -EBUSY;
+	}
 
 	/* Take MHI out of M2 state */
 	read_lock_bh(&mhi_cntrl->pm_lock);

@@ -900,6 +904,9 @@ int mhi_pm_suspend(struct mhi_controller *mhi_cntrl)
 	if (atomic_read(&mhi_cntrl->dev_wake) ||
 	    atomic_read(&mhi_cntrl->pending_pkts)) {
 		write_unlock_irq(&mhi_cntrl->pm_lock);
+		dev_err(dev, "DEBUG: suspend busy (recheck): dev_wake: %d pending_pkts: %d\n",
+			atomic_read(&mhi_cntrl->dev_wake),
+			atomic_read(&mhi_cntrl->pending_pkts));
 		return -EBUSY;
 	}
Signature · 1 line
2.45.2
Reviewed-by on v2 1/2
#3 lore raw

Re: [PATCH v2 1/2] bus: mhi: pci_generic: Prevent MHI from aborting system suspend

In reply to Len Brown
Quoted 16 lines · Len Brown

From: Len Brown <[email protected]>

mhi sometimes aborts system suspend on the thinkpad T16 gen3:

mhi-pci-generic 0000:08:00.0:
... failed to suspend device: -16
... PM: pci_pm_suspend(): mhi_pci_suspend [mhi_pci_generic] returns -16 ... PM: dpm_run_callback(): pci_pm_suspend returns -16
... PM: pci_pm_suspend returned -16 after 15145 usecs
... PM: failed to suspend async: error -16

Prevent MHI from spreading this device-specific failure to the rest of the system. I.e. "Why is a modem that I don't use preventing me from suspending my laptop?"

Quoted 8 lines

This change does not comprehend the internal root cause of the mhi failure, which should be found and fixed.

There is also a risk that ignoring the MHI error and continuing to put the device into PCI D3 will leave it in an error state.

Fixes d3800c1dce24 ("bus: mhi: pci_generic: Add support for runtime PM")
Signed-off-by Len Brown <[email protected]>
Reviewed-by Loic Poulain <[email protected]>
Quoted 25 lines
---
 drivers/bus/mhi/host/pci_generic.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
drivers/bus/mhi/host/pci_generic.c +6 -2
index 7193a384cca4..343d1046a25e 100644
@@ -1727,7 +1727,12 @@ static int __maybe_unused mhi_pci_runtime_resume(struct device *dev)
 static int  __maybe_unused mhi_pci_suspend(struct device *dev)
 {
        pm_runtime_disable(dev);
-       return mhi_pci_runtime_suspend(dev);
+
+       /* Ignore errors (e.g. -EBUSY); a failed modem suspend must not abort system suspend */
+       mhi_pci_runtime_suspend(dev);
+
+       /* Must return 0 to allow system suspend to continue */
+       return 0;
 }
 
 static int __maybe_unused mhi_pci_resume(struct device *dev)
--

2.45.2