linux-kernel - Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override.

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Date:	Wed, 02 Jan 2008 16:50:20 +0100
From:	Rene Herman <rene.herman@...access.nl>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
CC:	Ingo Molnar <mingo@...e.hu>, "David P. Reed" <dpreed@...d.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Rene Herman <rene.herman@...il.com>,
	Paul Rolland <rol@...917.net>, Pavel Machek <pavel@....cz>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
	rol@...be.net
Subject: Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override.

On 02-01-08 16:35, Rene Herman wrote:
 > On 02-01-08 14:47, Alan Cox wrote:
 >
 >>> ok, you are right. How about we go with one of your suggestions:
 >>> rename the API family to isa_*_p() in the affected ISA drivers? That
 >>> makes it perfectly clear that this is an ISA related historic quirk
 >>> that we just cannot properly emulate in an acceptable fashion. It
 >>> will also make the least amount of changes to these truly historic
 >>> drivers.
 >>
 >> Works for me. We need to build two versions of 8390.c now but thats no
 >> big deal and sorts PCMCIA out too.
 >
 > For no binary changes at all, and if going through all those outb_p()
 > users anyway, might/could as well just manually split them then:
 >
 > outb_p() --> outb();
 >              slow_down_io();
 >
 > and then just leave out the slow_down_io() call in the non-ISA spots.
 > slow_down_io() could be renamed isa_io_delay() or anything (paravirt is
 > a little annoying there) if someone cares but then it's a complete
 > identity transformation for any driver that does care.
 >
 > Would IMO also make for a somewhat better API than an isa_outb_p() as
 > there's nothing particurly ISA about the outb method itself -- many ISA
 > drivers use plain outb() as well.

Would just need this bit of io.h arch unification from the orignal patch and 
that's it:

diff --git a/include/asm-x86/io_64.h b/include/asm-x86/io_64.h
index a037b07..97cb8c6 100644
--- a/include/asm-x86/io_64.h
+++ b/include/asm-x86/io_64.h
@@ -35,13 +35,20 @@
    *  - Arnaldo Carvalho de Melo <acme@...ectiva.com.br>
    */

-#define __SLOW_DOWN_IO "\noutb %%al,$0x80"
+static inline void native_io_delay(void)
+{
+	asm volatile("outb %%al,$0x80" : : : "memory");
+}

+static inline void slow_down_io(void)
+{
+	native_io_delay();
  #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
+	native_io_delay();
+	native_io_delay();
+	native_io_delay();
  #endif
+}

  /*
   * Talk about misusing macros..
@@ -50,21 +57,21 @@
  static inline void out##s(unsigned x value, unsigned short port) {

  #define __OUT2(s,s1,s2) \
-__asm__ __volatile__ ("out" #s " %" s1 "0,%" s2 "1"
+__asm__ __volatile__ ("out" #s " %" s1 "0,%" s2 "1" : : "a" (value), "Nd" 
(port))

  #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,x) __OUT2(s,s1,"w"); } \
+__OUT1(s##_p,x) __OUT2(s,s1,"w"); slow_down_io(); }

  #define __IN1(s) \
  static inline RETURN_TYPE in##s(unsigned short port) { RETURN_TYPE _v;

  #define __IN2(s,s1,s2) \
-__asm__ __volatile__ ("in" #s " %" s2 "1,%" s1 "0"
+__asm__ __volatile__ ("in" #s " %" s2 "1,%" s1 "0" : "=a" (_v) : "Nd" (port))

-#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; } \
+#define __IN(s,s1) \
+__IN1(s) __IN2(s,s1,"w"); return _v; } \
+__IN1(s##_p) __IN2(s,s1,"w"); slow_down_io(); return _v; }

  #define __INS(s) \
  static inline void ins##s(unsigned short port, void * addr, unsigned long 
count) \

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