lkml.org 
[lkml]   [2002]   [Feb]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] NSC Geode Companion chip workaround
Date

Cyrix MediaGX/GXm or NSC Geode have PIT bug not TSC bug.
but in linux kernel, if CPU is Cyrix, then TSC flag is disabled.
This is not correct way, I think.

A patch atached below is originally from NetBSD kernel code.
In FreeBSD bug tracking system, this was discussed.

http://www.freebsd.org/cgi/query-pr.cgi?pr=6630

Here is NetBSD patch.
http://www.netbsd.org/cgi-bin/query-pr-single.pl?number=8654

in this patch, this code is activate only if you defines CONFIG_CS5520.
I've tryed several month with this patch, It seems good for me.
trial machine: Casio CASSIOPEIA FIVA 101 and Fiva 103.
MediaGX 200MHz and NSC Geode 300MHz.



diff -ur kernel-source-2.4.7/arch/i386/kernel/setup.c linux/arch/i386/kernel/setup.c
--- kernel-source-2.4.7/arch/i386/kernel/setup.c Thu Jul 12 01:31:44 2001
+++ linux/arch/i386/kernel/setup.c Fri Aug 10 21:12:06 2001
@@ -1425,14 +1425,18 @@
/* GXm supports extended cpuid levels 'ala' AMD */
if (c->cpuid_level == 2) {
get_model_name(c); /* get CPU marketing name */
+#ifndef CONFIG_CS5520
clear_bit(X86_FEATURE_TSC, c->x86_capability);
+#endif
return;
}
else { /* MediaGX */
Cx86_cb[2] = (dir0_lsn & 1) ? '3' : '4';
p = Cx86_cb+2;
c->x86_model = (dir1 & 0x20) ? 1 : 2;
+#ifndef CONFIG_CS5520
clear_bit(X86_FEATURE_TSC, &c->x86_capability);
+#endif
}
break;

diff -ur kernel-source-2.4.7/arch/i386/kernel/time.c linux/arch/i386/kernel/time.c
--- kernel-source-2.4.7/arch/i386/kernel/time.c Sat Dec 30 07:07:57 2000
+++ linux/arch/i386/kernel/time.c Fri Aug 10 21:04:26 2001
@@ -28,6 +28,9 @@
* 1998-12-24 Copyright (C) 1998 Andrea Arcangeli
* Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
* serialize accesses to xtime/lost_ticks).
+ * 2001-02-20 Hiroshi Miura <miura@da-cha.org>
+ * Work around for Cyrix/IBM/NSC MediaGX/GXm, NSC Geode southbridge
+ * PIT bug. (NSC Cx5510/5520)
*/

#include <linux/errno.h>
@@ -459,6 +462,10 @@
static void timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
int count;
+#ifdef CONFIG_CS5520
+ int count1, count2, count3;
+ int n1, n2, n3;
+#endif

/*
* Here we are in the timer irq handler. We just have irqs locally
@@ -487,6 +494,7 @@

rdtscl(last_tsc_low);

+#ifndef CONFIG_CS5520
spin_lock(&i8253_lock);
outb_p(0x00, 0x43); /* latch the count ASAP */

@@ -499,6 +507,59 @@
}

do_timer_interrupt(irq, NULL, regs);
+#else
+ spin_lock(&i8253_lock);
+ outb_p(0x00, 0x43); /* latch the count ASAP */
+/* this codes comes from FreeBSD */
+ count1 = inb_p(0x40);
+ count1 |= inb(0x40) << 8;
+ count2 = inb_p(0x40);
+ count2 = inb(0x40) << 8;
+ count3 = inb_p(0x40);
+ count3 = inb(0x40) << 8;
+ spin_unlock(&i8253_lock);
+
+ if (count1 >= count2 && count2 >= count3 && count1 - count2 < 0x200)
+ count = count2;
+ else {
+
+#define _swap_val(a, b) do { \
+ int c = a;\
+ a = b; \
+ b = c; \
+} while(0)
+ /* sort values */
+ if (count1 < count2)
+ _swap_val(count1, count2);
+ if (count2 < count3)
+ _swap_val(count2, count3);
+ if (count1 < count2)
+ _swap_val(count1, count2);
+
+ /* compare the middle value */
+ if (count1 - count3 < 0x200)
+ count = count2;
+ else
+ {
+ n1 = count2 - count3;
+ n2 = count3 - count1 + LATCH;
+ n3 = count1 - count2;
+ count = count3;
+ if (n1 >= n2) {
+ if (n1 >= n3)
+ count = count1;
+ } else {
+ if (n2 >= n3)
+ count = count2;
+ }
+ }
+ }
+ count = ((LATCH-1) - count) * TICK_SIZE;
+ delay_at_last_interrupt = (count + LATCH/2) / LATCH;
+ }
+
+ do_timer_interrupt(irq, NULL, regs);
+#endif

write_unlock(&xtime_lock);

@@ -659,6 +720,9 @@

if (cpu_has_tsc) {
unsigned long tsc_quotient = calibrate_tsc();
+#ifdef CONFIG_CS5520
+ if (!tsc_quotient) tsc_quotient = calibrate_tsc();
+#endif
if (tsc_quotient) {
fast_gettimeoffset_quotient = tsc_quotient;
use_tsc = 1;

Hiroshi Miura --- miura@da-cha.org http://www.da-cha.org/
CCNA, Oracle Silver Master, Network Specialist(JITEC)
My interest: http://www.cis.com.tw/Product/WS-U50R.htm










-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:24    [W:0.568 / U:0.516 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site