Re: [PATCH] x86_64: fix problems due to use of "outb" to port 80 on some AMD64x2 laptops, etc.

[Ingo Molnar <mingo@elte.hu>]

> > updated patch attached. (from the MakeItBuild'n'Stuff dept)
> 
> the one below is against current upstream. (previous ones were against 
> x86.git)

the last version is the one below. Pending further discussion and 
testing. And David, i nominate your fix as the coolest Linux kernel fix 
of 2007 :-)

	Ingo

-------------------------------->

Subject: x86: fix in_p/out_p crashes
From: David P. Reed <dpreed@reed.com>

Do not use port 0x80, it can cause crashes, see:

 http://bugzilla.kernel.org/show_bug.cgi?id=6307
 http://bugzilla.kernel.org/show_bug.cgi?id=9511

Replace use of outb to "unused" diagnostic port 0x80 for time delay
with udelay based time delay on x86_64 architecture machines.  Fix for
bugs 9511 and 6307 in bugzilla, plus bugs reported in
bugzilla.redhat.com.

Derived from suggestion (that didn't compile) by Pavel Machek, and
tested, also based on measurements of typical timings of out's
collated by Rene Herman from many in the community.

This patch fixes a number of bugs known to cause problems on HP
Pavilion dv9000z and dv6000z laptops - in the form of solid freezes
when hwclock is used to show or set the time.  Also, it potentially
improves bus utilization on SMP machines, by using a waiting process
that doesn't tie up the ISA/LPC bus for 1 or 2 microseconds.

[ mingo@elte.hu: minor restructuring, 32-bit support. ]

Signed-off-by: David P. Reed <dpreed@reed.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 arch/x86/boot/compressed/misc_32.c |    8 ++++----
 arch/x86/boot/compressed/misc_64.c |    8 ++++----
 arch/x86/kernel/quirks.c           |   10 ++++++++++
 include/asm-x86/io_32.h            |    5 +----
 include/asm-x86/io_64.h            |   14 +++++---------
 5 files changed, 24 insertions(+), 21 deletions(-)

Index: linux-x86.q/arch/x86/boot/compressed/misc_32.c
===================================================================
--- linux-x86.q.orig/arch/x86/boot/compressed/misc_32.c
+++ linux-x86.q/arch/x86/boot/compressed/misc_32.c
@@ -276,10 +276,10 @@ static void putstr(const char *s)
 	RM_SCREEN_INFO.orig_y = y;
 
 	pos = (x + cols * y) * 2;	/* Update cursor position */
-	outb_p(14, vidport);
-	outb_p(0xff & (pos >> 9), vidport+1);
-	outb_p(15, vidport);
-	outb_p(0xff & (pos >> 1), vidport+1);
+	outb(14, vidport);
+	outb(0xff & (pos >> 9), vidport+1);
+	outb(15, vidport);
+	outb(0xff & (pos >> 1), vidport+1);
 }
 
 static void* memset(void* s, int c, unsigned n)
Index: linux-x86.q/arch/x86/boot/compressed/misc_64.c
===================================================================
--- linux-x86.q.orig/arch/x86/boot/compressed/misc_64.c
+++ linux-x86.q/arch/x86/boot/compressed/misc_64.c
@@ -269,10 +269,10 @@ static void putstr(const char *s)
 	RM_SCREEN_INFO.orig_y = y;
 
 	pos = (x + cols * y) * 2;	/* Update cursor position */
-	outb_p(14, vidport);
-	outb_p(0xff & (pos >> 9), vidport+1);
-	outb_p(15, vidport);
-	outb_p(0xff & (pos >> 1), vidport+1);
+	outb(14, vidport);
+	outb(0xff & (pos >> 9), vidport+1);
+	outb(15, vidport);
+	outb(0xff & (pos >> 1), vidport+1);
 }
 
 static void* memset(void* s, int c, unsigned n)
Index: linux-x86.q/arch/x86/kernel/quirks.c
===================================================================
--- linux-x86.q.orig/arch/x86/kernel/quirks.c
+++ linux-x86.q/arch/x86/kernel/quirks.c
@@ -3,9 +3,19 @@
  */
 #include <linux/pci.h>
 #include <linux/irq.h>
+#include <linux/delay.h>
 
 #include <asm/hpet.h>
 
+/*
+ * Some legacy devices need delays for IN/OUT sequences. Most are
+ * probably not needed but it's the safest to just do this short delay:
+ */
+void native_io_delay(void)
+{
+	udelay(2);
+}
+
 #if defined(CONFIG_X86_IO_APIC) && defined(CONFIG_SMP) && defined(CONFIG_PCI)
 
 static void __devinit quirk_intel_irqbalance(struct pci_dev *dev)
Index: linux-x86.q/include/asm-x86/io_32.h
===================================================================
--- linux-x86.q.orig/include/asm-x86/io_32.h
+++ linux-x86.q/include/asm-x86/io_32.h
@@ -250,10 +250,7 @@ static inline void flush_write_buffers(v
 
 #endif /* __KERNEL__ */
 
-static inline void native_io_delay(void)
-{
-	asm volatile("outb %%al,$0x80" : : : "memory");
-}
+extern void native_io_delay(void);
 
 #if defined(CONFIG_PARAVIRT)
 #include <asm/paravirt.h>
Index: linux-x86.q/include/asm-x86/io_64.h
===================================================================
--- linux-x86.q.orig/include/asm-x86/io_64.h
+++ linux-x86.q/include/asm-x86/io_64.h
@@ -35,13 +35,7 @@
   *  - Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   */
 
-#define __SLOW_DOWN_IO "\noutb %%al,$0x80"
-
-#ifdef REALLY_SLOW_IO
-#define __FULL_SLOW_DOWN_IO __SLOW_DOWN_IO __SLOW_DOWN_IO __SLOW_DOWN_IO __SLOW_DOWN_IO
-#else
-#define __FULL_SLOW_DOWN_IO __SLOW_DOWN_IO
-#endif
+extern void native_io_delay(void);
 
 /*
  * Talk about misusing macros..
@@ -54,7 +48,8 @@ __asm__ __volatile__ ("out" #s " %" s1 "
 
 #define __OUT(s,s1,x) \
 __OUT1(s,x) __OUT2(s,s1,"w") : : "a" (value), "Nd" (port)); } \
-__OUT1(s##_p,x) __OUT2(s,s1,"w") __FULL_SLOW_DOWN_IO : : "a" (value), "Nd" (port));} \
+__OUT1(s##_p,x) __OUT2(s,s1,"w") : : "a" (value), "Nd" (port)); \
+native_io_delay(); } \
 
 #define __IN1(s) \
 static inline RETURN_TYPE in##s(unsigned short port) { RETURN_TYPE _v;
@@ -64,7 +59,8 @@ __asm__ __volatile__ ("in" #s " %" s2 "1
 
 #define __IN(s,s1,i...) \
 __IN1(s) __IN2(s,s1,"w") : "=a" (_v) : "Nd" (port) ,##i ); return _v; } \
-__IN1(s##_p) __IN2(s,s1,"w") __FULL_SLOW_DOWN_IO : "=a" (_v) : "Nd" (port) ,##i ); return _v; } \
+__IN1(s##_p) __IN2(s,s1,"w") : "=a" (_v) : "Nd" (port) ,##i ); return _v; \
+native_io_delay(); } \
 
 #define __INS(s) \
 static inline void ins##s(unsigned short port, void * addr, unsigned long count) \