[linux-yocto] [PATCH 3/7] PCI / PM: Tune down retryable runtime suspend error messages

Yong, Jonathan jonathan.yong at intel.com
Wed Jun 29 18:03:19 PDT 2016

From: Imre Deak <imre.deak at intel.com>

The runtime PM core doesn't treat EBUSY and EAGAIN retvals from the driver
suspend hooks as errors, but they still show up as errors in dmesg. Tune
them down. See rpm_suspend() for details of handling these return values.

Note that we use dev_dbg() for the retryable retvals, so after this
change you'll need either CONFIG_DYNAMIC_DEBUG or CONFIG_PCI_DEBUG
for them to show up in the log.

One problem caused by this was noticed by Daniel: the i915 driver
returns EAGAIN to signal a temporary failure to suspend and as a request
towards the RPM core for scheduling a suspend again. This is a normal
event, but the resulting error message flags a breakage during the
driver's automated testing which parses dmesg and picks up the error.

Reported-by: Daniel Vetter <daniel.vetter at intel.com>
Link: https://bugs.freedesktop.org/show_bug.cgi?id=92992
Signed-off-by: Imre Deak <imre.deak at intel.com>
Acked-by: Bjorn Helgaas <bhelgaas at google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
Signed-off-by: Yong, Jonathan <jonathan.yong at intel.com>
 drivers/pci/pci-driver.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 3cb2210..a523550 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -1127,9 +1127,21 @@ static int pci_pm_runtime_suspend(struct device *dev)
 	pci_dev->state_saved = false;
 	pci_dev->no_d3cold = false;
 	error = pm->runtime_suspend(dev);
-	suspend_report_result(pm->runtime_suspend, error);
-	if (error)
+	if (error) {
+		/*
+		 * -EBUSY and -EAGAIN is used to request the runtime PM core
+		 * to schedule a new suspend, so log the event only with debug
+		 * log level.
+		 */
+		if (error == -EBUSY || error == -EAGAIN)
+			dev_dbg(dev, "can't suspend now (%pf returned %d)\n",
+				pm->runtime_suspend, error);
+		else
+			dev_err(dev, "can't suspend (%pf returned %d)\n",
+				pm->runtime_suspend, error);
 		return error;
+	}
 	if (!pci_dev->d3cold_allowed)
 		pci_dev->no_d3cold = true;

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