Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops

Ingo Molnar
2007-12-17T14:43:44Z

* Pavel Machek <pavel@ucw.cz> wrote:

> > > > ./char/epca.c
> > > > ./char/sonypi.c
> > > > ./scsi/megaraid.c
> > > > ./ide/pci/serverworks.c
> > > > ./ide/pci/cmd640.c
> > > > ./input/mouse/pc110pad.c
> >
> > You are missing some watchdogs at least ?
>
> I snipped them, I only wanted to comment that pc110pad.c looks like
> legitimate use of outb_p().

since this code seems to run late during bootup (a mouse driver), could
we replace this with udelay(2), and get rid of that outb_p()? I.e. via
the patch below?

Ingo

----------------->
Subject: x86: replace outb_p() with udelay(2) in drivers/input/mouse/pc110pad.c
From: Ingo Molnar <mingo@elte.hu>

replace outb_p() with udelay(2). This is a real ISA device so it likely
needs this particular delay.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
drivers/input/mouse/pc110pad.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

Index: linux-x86.q/drivers/input/mouse/pc110pad.c
===================================================================
--- linux-x86.q.orig/drivers/input/mouse/pc110pad.c
+++ linux-x86.q/drivers/input/mouse/pc110pad.c
@@ -39,6 +39,7 @@
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/pci.h>
+#include <linux/delay.h>

#include <asm/io.h>
#include <asm/irq.h>
@@ -62,8 +63,10 @@ static irqreturn_t pc110pad_interrupt(in
int value = inb_p(pc110pad_io);
int handshake = inb_p(pc110pad_io + 2);

- outb_p(handshake | 1, pc110pad_io + 2);
- outb_p(handshake & ~1, pc110pad_io + 2);
+ outb(handshake | 1, pc110pad_io + 2);
+ udelay(2);
+ outb(handshake & ~1, pc110pad_io + 2);
+ udelay(2);
inb_p(0x64);

pc110pad_data[pc110pad_count++] = value;