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

Pavel Machek
2007-12-27T10:40:03Z

On Mon 2007-12-17 15:42:51, Ingo Molnar wrote:
>
> * 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?

Yes, that should work. But I do not have pc110 to verify it.
>
> 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>

ACK.

> 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;
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