Hi all,
Please find attached a patch to close a race between the e500 PowerPC
decrementer wrapping and the associated tick interrupt handler doing its
thing.
The issue came up in the users@ list:
http://lists.rtems.org/pipermail/users/2014-November/028362.html
With these changes and not without, the spnsext01 test passes on the
MVME3100.
--
Nick Withers
Embedded Systems Programmer
Department of Nuclear Physics, Research School of Physics and Engineering
The Australian National University (CRICOS: 00120C)
>From 9c21d107fa7fc109663f97d4a07fbc7f184d02bd Mon Sep 17 00:00:00 2001
From: Nick Withers <nick.with...@anu.edu.au>
Date: Fri, 14 Nov 2014 11:49:18 +1100
Subject: [PATCH] Correct a race condition between the e500 core decrementer
wrapping and the tick interrupt being handled.
This corrects a "time-going-backwards" problem.
The decrementer is now manually reset in the tick handler, as for the
non-e500 case
---
c/src/lib/libbsp/powerpc/shared/clock/p_clock.c | 4 ----
c/src/lib/libcpu/powerpc/mpc6xx/clock/c_clock.c | 32 ++-----------------------
2 files changed, 2 insertions(+), 34 deletions(-)
diff --git a/c/src/lib/libbsp/powerpc/shared/clock/p_clock.c b/c/src/lib/libbsp/powerpc/shared/clock/p_clock.c
index 1ff7ca0..15b0abf 100644
--- a/c/src/lib/libbsp/powerpc/shared/clock/p_clock.c
+++ b/c/src/lib/libbsp/powerpc/shared/clock/p_clock.c
@@ -17,7 +17,6 @@
#include <bsp.h>
#include <bsp/irq.h>
#include <libcpu/c_clock.h>
-#include <libcpu/cpuIdent.h>
static rtems_irq_connect_data clockIrqData;
static rtems_irq_connect_data clockIrqData = {
@@ -36,8 +35,5 @@ int BSP_disconnect_clock_handler(void)
int BSP_connect_clock_handler(void)
{
- if ( ppc_cpu_is_bookE() )
- clockIrqData.hdl = clockIsrBookE;
-
return BSP_install_rtems_irq_handler(&clockIrqData);
}
diff --git a/c/src/lib/libcpu/powerpc/mpc6xx/clock/c_clock.c b/c/src/lib/libcpu/powerpc/mpc6xx/clock/c_clock.c
index f14acab..d1ce441 100644
--- a/c/src/lib/libcpu/powerpc/mpc6xx/clock/c_clock.c
+++ b/c/src/lib/libcpu/powerpc/mpc6xx/clock/c_clock.c
@@ -34,7 +34,6 @@
SPR_RW(BOOKE_TCR)
SPR_RW(BOOKE_TSR)
-SPR_RW(BOOKE_DECAR)
extern int BSP_connect_clock_handler (void);
@@ -71,8 +70,6 @@ void clockOn(void* unused)
PPC_Set_decrementer( Clock_Decrementer_value );
if ( ppc_cpu_is_bookE() ) {
- _write_BOOKE_DECAR( Clock_Decrementer_value );
-
rtems_interrupt_disable(l);
/* clear pending/stale irq */
@@ -143,30 +140,6 @@ void clockIsr(void *unused)
} while ( decr < 0 );
}
-/*
- * Clock_isr_bookE
- *
- * This is the clock tick interrupt handler
- * for bookE CPUs. For efficiency reasons we
- * provide a separate handler rather than
- * checking the CPU type each time.
- */
-void clockIsrBookE(void *unused)
-{
- /* Note: TSR bit has already been cleared in the exception handler */
-
- /*
- * The driver has seen another tick.
- */
-
- Clock_driver_ticks += 1;
-
- /*
- * Real Time Clock counter/timer is set to automatically reload.
- */
- clock_handler();
-}
-
int clockIsOn(void* unused)
{
uint32_t msr_value;
@@ -230,15 +203,14 @@ rtems_device_driver Clock_initialize(
*/
PPC_Set_decrementer( (unsigned)-1 );
- /* On a bookE CPU the decrementer works differently. It doesn't
- * count past zero but we can enable auto-reload :-)
+ /*
+ * On a bookE CPU the decrementer works differently
*/
if ( ppc_cpu_is_bookE() ) {
rtems_interrupt_disable(l);
tcr = _read_BOOKE_TCR();
- tcr |= BOOKE_TCR_ARE;
tcr &= ~BOOKE_TCR_DIE;
_write_BOOKE_TCR(tcr);
--
2.1.2
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