[PATCH v2 1/2] PM: runtime: Only set runtime_error on suspend callback failures

[Praveen Talari]

When a runtime resume callback returns an error, rpm_callback() sets
power.runtime_error on the device.  This causes all subsequent calls to
rpm_resume() to return -EINVAL immediately at the top of the function
without invoking the callback again, making the failure permanent until
runtime PM is explicitly re-initialized.

Unlike suspend failures, resume failures should be retryable.  If a
device's resume callback fails transiently, there is no reason to
permanently block future resume attempts on that device and all of its
consumers.

Fix this by conditioning the power.runtime_error assignment in
rpm_callback() on the device being in the RPM_SUSPENDING state.  At the
point rpm_callback() runs, __update_runtime_status() has already set the
device status to either RPM_SUSPENDING or RPM_RESUMING, so the two paths
are reliably distinguishable.  Suspend callback failures continue to set
power.runtime_error as before.  Resume callback failures return the error
to the caller but leave power.runtime_error clear, allowing the next
resume attempt to invoke the callback normally.

Signed-off-by: Praveen Talari <praveen.talari@xxxxxxxxxxxxxxxx>
---
 drivers/base/power/runtime.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 335288e8b5b3..70d933bcd295 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -469,7 +469,13 @@ static int rpm_callback(int (*cb)(struct device *), struct device *dev)
 	if (retval == -EACCES)
 		retval = -EAGAIN;
 
-	if (retval != -EAGAIN && retval != -EBUSY)
+	/*
+	 * Only stick the error on suspend failures.  Resume failures are not
+	 * treated as permanent so that the next resume attempt will run the
+	 * callback again rather than short-circuiting on runtime_error.
+	 */
+	if (retval != -EAGAIN && retval != -EBUSY &&
+	    dev->power.runtime_status == RPM_SUSPENDING)
 		dev->power.runtime_error = retval;
 
 	return retval;

-- 
2.34.1