PM: runtime: Unify error handling during suspend and resume

There is a confusing difference in error handling between rpm_suspend()
and rpm_resume() related to the special way in which -EAGAIN and -EBUSY
error values are treated by the former. Also, converting -EACCES coming
from the callback to I/O error, which it quite likely is not, may
confuse runtime PM users.

To address the above, modify rpm_callback() to convert -EACCES coming
from the driver to -EAGAIN and to set power.runtime_error only if the
return value is not -EAGAIN or -EBUSY.

This will cause the error handling in rpm_resume() and rpm_suspend() to
work consistently, so drop the no longer needed -EAGAIN or -EBUSY
special case from the latter and make it retry autosuspend if
power.runtime_error is unset.

Signed-off-by: Rafael J. Wysocki <[e-mail]>
Reviewed-by: Ulf Hansson <[e-mail]>
Link: https://patch.msgid.link/[e-mail]

drivers/base/power/runtime.c

···
 		retval = __rpm_callback(cb, dev);
 	}
 
-	dev->power.runtime_error = retval;
-	return retval != -EACCES ? retval : -EIO;
+	/*
+	 * Since -EACCES means that runtime PM is disabled for the given device,
+	 * it should not be returned by runtime PM callbacks.  If it is returned
+	 * nevertheless, assume it to be a transient error and convert it to
+	 * -EAGAIN.
+	 */
+	if (retval == -EACCES)
+		retval = -EAGAIN;
+
+	if (retval != -EAGAIN && retval != -EBUSY)
+		dev->power.runtime_error = retval;
+
+	return retval;
 }
 
 /**
···
 	dev->power.deferred_resume = false;
 	wake_up_all(&dev->power.wait_queue);
 
-	if (retval == -EAGAIN || retval == -EBUSY) {
-		dev->power.runtime_error = 0;
+	/*
+	 * On transient errors, if the callback routine failed an autosuspend,
+	 * and if the last_busy time has been updated so that there is a new
+	 * autosuspend expiration time, automatically reschedule another
+	 * autosuspend.
+	 */
+	if (!dev->power.runtime_error && (rpmflags & RPM_AUTO) &&
+	    pm_runtime_autosuspend_expiration(dev) != 0)
+		goto repeat;
 
-		/*
-		 * If the callback routine failed an autosuspend, and
-		 * if the last_busy time has been updated so that there
-		 * is a new autosuspend expiration time, automatically
-		 * reschedule another autosuspend.
-		 */
-		if ((rpmflags & RPM_AUTO) &&
-		    pm_runtime_autosuspend_expiration(dev) != 0)
-			goto repeat;
-	} else {
-		pm_runtime_cancel_pending(dev);
-	}
+	pm_runtime_cancel_pending(dev);
+
 	goto out;
 }