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* [PATCH] x86: define outb_pic and inb_pic to stop using outb_p and inb_p
@ 2008-02-18 18:58 David P. Reed
  2008-02-19  9:42 ` Ingo Molnar
  0 siblings, 1 reply; 2+ messages in thread
From: David P. Reed @ 2008-02-18 18:58 UTC (permalink / raw)
  To: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, Alan Cox, Rene Herman
  Cc: linux-kernel, David P. Reed

x86: define outb_pic and inb_pic to stop using outb_p and inb_p
 
The delay between io port accesses to the PIC is now defined using outb_pic
and inb_pic.  This fix provides the next step, using udelay(2) to define the
*PIC specific* timing requirements, rather than on bus-oriented timing, which
is not well calibrated.

Again, the primary reason for fixing this is to use proper delay strategy,
and in particular to fix crashes that can result from using port 80 writes
on machines that have resources on port 80, such as the ENE chips used by Quanta
in latops it designs and sells to, e.g. HP.

Signed-off-by: David P. Reed <dpreed@reed.com>
Index: linux-2.6/include/asm-x86/i8259.h
===================================================================
--- linux-2.6.orig/include/asm-x86/i8259.h
+++ linux-2.6/include/asm-x86/i8259.h
@@ -29,7 +29,23 @@ extern void enable_8259A_irq(unsigned in
 extern void disable_8259A_irq(unsigned int irq);
 extern unsigned int startup_8259A_irq(unsigned int irq);
 
-#define inb_pic		inb_p
-#define outb_pic	outb_p
+/* the PIC may need a careful delay on some platforms, hence specific calls */
+static inline unsigned char inb_pic(unsigned int port)
+{
+	/* delay for some accesses to PIC on motherboard or in chipset must be
+	   at least one microsecond, but be safe here. */
+	unsigned char value = inb(port);
+	udelay(2);
+	return value;
+}
+
+static inline void outb_pic(unsigned char value, unsigned int port)
+{
+	/* delay for some accesses to PIC on motherboard or in chipset must be
+	   at least one microsecond, but be safe here. */
+	outb(value, port);
+	udelay(2);
+}
+
 
 #endif	/* __ASM_I8259_H__ */

-- 

^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [PATCH] x86: define outb_pic and inb_pic to stop using outb_p and inb_p
  2008-02-18 18:58 [PATCH] x86: define outb_pic and inb_pic to stop using outb_p and inb_p David P. Reed
@ 2008-02-19  9:42 ` Ingo Molnar
  0 siblings, 0 replies; 2+ messages in thread
From: Ingo Molnar @ 2008-02-19  9:42 UTC (permalink / raw)
  To: David P. Reed
  Cc: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, Alan Cox,
	Rene Herman, linux-kernel


* David P. Reed <dpreed@reed.com> wrote:

> x86: define outb_pic and inb_pic to stop using outb_p and inb_p
>  
> The delay between io port accesses to the PIC is now defined using 
> outb_pic and inb_pic.  This fix provides the next step, using 
> udelay(2) to define the *PIC specific* timing requirements, rather 
> than on bus-oriented timing, which is not well calibrated.

thanks David, applied.

minor nit:

> +	/* delay for some accesses to PIC on motherboard or in chipset must be
> +	   at least one microsecond, but be safe here. */

i changed this to the standard multi-line comment style of:

> +	/*
> +      * Delay for some accesses to PIC on motherboard or in chipset 
> +      * must be at least one microsecond, but be safe here:
> +      */

	Ingo

^ permalink raw reply	[flat|nested] 2+ messages in thread

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