[PATCH]: Add command-line option to i8042 to completely disable it

[PATCH]: Add command-line option to i8042 to completely disable it

[Chris Lalancette]

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(I tried to send this patch to linux-input@, but it seems to be currently having
some problems, so I'm going directly to LKML).

Certain (broken) pieces of South Bridge hardware will respond to
i8042_read_status() on boot with 0x0, despite there not being a real i8042
controller hooked up in the south bridge.  This can cause the detection for the
i8042 to return a "phantom" device, which hangs up later initialization.  Note
that using "i8042.nokbd" and/or "i8042.noaux" do not help with this, since this
shows up during i8042_controller_check() (before either of those options are
checked).  This patch adds a command-line option "i8042.disable", which just
completely disables any checking for the i8042 controller.

Signed-off-by: Chris Lalancette <clalance@redhat.com>




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diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index 3888dc3..a13039c 100644
--- a/drivers/input/serio/i8042.c
+++ b/drivers/input/serio/i8042.c
@@ -27,6 +27,10 @@ MODULE_AUTHOR("Vojtech Pavlik <vojtech@suse.cz>");
 MODULE_DESCRIPTION("i8042 keyboard and mouse controller driver");
 MODULE_LICENSE("GPL");
 
+static unsigned int i8042_disable;
+module_param_named(disable, i8042_disable, bool, 0);
+MODULE_PARM_DESC(disable, "Do not probe i8042 at all.");
+
 static unsigned int i8042_nokbd;
 module_param_named(nokbd, i8042_nokbd, bool, 0);
 MODULE_PARM_DESC(nokbd, "Do not probe or use KBD port.");
@@ -1194,6 +1198,11 @@ static int __init i8042_init(void)
 {
 	int err;
 
+	if (i8042_disable) {
+		printk(KERN_ERR "i8042.c: Controller disabled by kernel command-line\n");
+		return -ENODEV;
+	}
+
 	dbg_init();
 
 	err = i8042_platform_init();

Re: [PATCH]: Add command-line option to i8042 to completely disable it

[Andrew Morton]

On Mon, 23 Jul 2007 13:05:22 -0400 Chris Lalancette <clalance@redhat.com> wrote:

> (I tried to send this patch to linux-input@, but it seems to be currently having
> some problems, so I'm going directly to LKML).
> 
> Certain (broken) pieces of South Bridge hardware will respond to
> i8042_read_status() on boot with 0x0, despite there not being a real i8042
> controller hooked up in the south bridge.  This can cause the detection for the
> i8042 to return a "phantom" device, which hangs up later initialization.  Note
> that using "i8042.nokbd" and/or "i8042.noaux" do not help with this, since this
> shows up during i8042_controller_check() (before either of those options are
> checked).  This patch adds a command-line option "i8042.disable", which just
> completely disables any checking for the i8042 controller.

That's an unfortunate fix.  Is there really no way in which we
can auto-detect such a situation without requiring a manual
setting?

Re: [PATCH]: Add command-line option to i8042 to completely disable it

[Vojtech Pavlik]

On Wed, Jul 25, 2007 at 12:05:04AM -0700, Andrew Morton wrote:
> On Mon, 23 Jul 2007 13:05:22 -0400 Chris Lalancette <clalance@redhat.com> wrote:
> 
> > (I tried to send this patch to linux-input@, but it seems to be currently having
> > some problems, so I'm going directly to LKML).
> > 
> > Certain (broken) pieces of South Bridge hardware will respond to
> > i8042_read_status() on boot with 0x0, despite there not being a real i8042
> > controller hooked up in the south bridge.  This can cause the detection for the
> > i8042 to return a "phantom" device, which hangs up later initialization.  Note
> > that using "i8042.nokbd" and/or "i8042.noaux" do not help with this, since this
> > shows up during i8042_controller_check() (before either of those options are
> > checked).  This patch adds a command-line option "i8042.disable", which just
> > completely disables any checking for the i8042 controller.
> 
> That's an unfortunate fix.  Is there really no way in which we
> can auto-detect such a situation without requiring a manual
> setting?

The fact that the current detection hangs suggests that the scenario is
possible to detect.

-- 
Vojtech Pavlik
Director SuSE Labs

Re: [PATCH]: Add command-line option to i8042 to completely disable it

[Chris Lalancette]

Vojtech Pavlik wrote:
>>
>>That's an unfortunate fix.  Is there really no way in which we
>>can auto-detect such a situation without requiring a manual
>>setting?
> 
> 
> The fact that the current detection hangs suggests that the scenario is
> possible to detect.
> 

Hm, OK.  I'll go back and look at i8042_flush() to see if I can detect this
erroneous situation automatically and fail the i8042_controller_init() if I see it.

Chris Lalancette