svn commit: r320074 - head/sys/arm/arm

[Ian Lepore]

Author: ian
Date: Sun Jun 18 17:26:54 2017
New Revision: 320074
URL: https://svnweb.freebsd.org/changeset/base/320074

Log:
  Only register as the platform DELAY() implementation if the setup of the
  global timer was successful, since the implementation tries to read it.
  
  Notably, if the platform has a variable-frequency global timer (because
  of dynamic frequency scaling), it doesn't set up the global timer for use
  as a system timecounter, and in that case it also can't use it for DELAY.
  Such platforms use different timer hardware for both timecounter and DELAY.

Modified:
  head/sys/arm/arm/mpcore_timer.c

Modified: head/sys/arm/arm/mpcore_timer.c
==============================================================================
--- head/sys/arm/arm/mpcore_timer.c	Sun Jun 18 17:20:48 2017	(r320073)
+++ head/sys/arm/arm/mpcore_timer.c	Sun Jun 18 17:26:54 2017	(r320074)
@@ -439,7 +439,12 @@ arm_tmr_attach(device_t dev)
 	}
 
 #ifdef MULTIDELAY
-	arm_set_delay(arm_tmr_delay, sc);
+	/*
+	 * We can register as the DELAY() implementation only if we successfully
+	 * set up the global timer.
+	 */
+	if (tc_err == 0)
+		arm_set_delay(arm_tmr_delay, sc);
 #endif
 
 	return (0);