From cc726b9ffd38771454660d5bd6b4f197707e40d7 Mon Sep 17 00:00:00 2001
From: AJFISH <AJFISH@6f19259b-4bc3-4df7-8a09-765794883524>
Date: Fri, 8 Jan 2010 21:03:12 +0000
Subject: update comments

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@9694 6f19259b-4bc3-4df7-8a09-765794883524
---
 EmbeddedPkg/TemplateTimerDxe/Timer.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

(limited to 'EmbeddedPkg')

diff --git a/EmbeddedPkg/TemplateTimerDxe/Timer.c b/EmbeddedPkg/TemplateTimerDxe/Timer.c
index 4bfa3e8622..a48d4b52eb 100644
--- a/EmbeddedPkg/TemplateTimerDxe/Timer.c
+++ b/EmbeddedPkg/TemplateTimerDxe/Timer.c
@@ -72,7 +72,11 @@ TimerInterruptHandler (
 {
 	EFI_TPL							OriginalTPL;
 
-  // Mask all interrupts
+  //
+  // DXE core uses this callback for the EFI timer tick. The DXE core uses locks 
+  // that raise to TPL_HIGH and then restore back to current level. Thus we need
+  // to make sure TPL level is set to TPL_HIGH while we are handling the timer tick. 
+  //
 	OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
 
   MmioWrite32 (TIMER_CMD, 0);
-- 
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