diff mbox

Regression: Dell XPS 13 9360 keyboard no longer works

Message ID 88473a72368b43bdacebca279092ab0f@ausx13mpc120.AMER.DELL.COM (mailing list archive)
State Superseded, archived
Headers show

Commit Message

Limonciello, Mario Feb. 22, 2018, 5:05 p.m. UTC
> -----Original Message-----

> From: platform-driver-x86-owner@vger.kernel.org [mailto:platform-driver-x86-

> owner@vger.kernel.org] On Behalf Of Jeremy Cline

> Sent: Thursday, February 22, 2018 10:42 AM

> To: Limonciello, Mario <Mario_Limonciello@Dell.com>; notmart@gmail.com

> Cc: pali.rohar@gmail.com; andriy.shevchenko@linux.intel.com;

> mjg59@srcf.ucam.org; dvhart@infradead.org; platform-driver-

> x86@vger.kernel.org; linux-kernel@vger.kernel.org

> Subject: Re: Regression: Dell XPS 13 9360 keyboard no longer works

> 

> On 02/22/2018 11:17 AM, Mario.Limonciello@dell.com wrote:

> >> -----Original Message-----

> >> From: platform-driver-x86-owner@vger.kernel.org [mailto:platform-driver-x86-

> >> owner@vger.kernel.org] On Behalf Of Jeremy Cline

> >> Sent: Thursday, February 22, 2018 10:17 AM

> >> To: Limonciello, Mario <Mario_Limonciello@Dell.com>; notmart@gmail.com

> >> Cc: pali.rohar@gmail.com; andriy.shevchenko@linux.intel.com;

> >> mjg59@srcf.ucam.org; dvhart@infradead.org; platform-driver-

> >> x86@vger.kernel.org; linux-kernel@vger.kernel.org

> >> Subject: Re: Regression: Dell XPS 13 9360 keyboard no longer works

> >>

> >> On 02/22/2018 11:14 AM, Mario.Limonciello@dell.com wrote:

> >>>> -----Original Message-----

> >>>> From: Jeremy Cline [mailto:jeremy@jcline.org]

> >>>> Sent: Thursday, February 22, 2018 9:59 AM

> >>>> To: Limonciello, Mario <Mario_Limonciello@Dell.com>; notmart@gmail.com

> >>>> Cc: pali.rohar@gmail.com; andriy.shevchenko@linux.intel.com;

> >>>> mjg59@srcf.ucam.org; dvhart@infradead.org; platform-driver-

> >>>> x86@vger.kernel.org; linux-kernel@vger.kernel.org

> >>>> Subject: Re: Regression: Dell XPS 13 9360 keyboard no longer works

> >>>>

> >>>> On 02/22/2018 10:21 AM, Mario.Limonciello@dell.com wrote:> I guess that

> >>>> means we got this wrong and the patch should be reverted

> >>>>> until we figure this out.

> >>>>>

> >>>>> Jeremy,

> >>>>>

> >>>>> Can you please confirm what BIOS version you are on?

> >>>>> Also Is this a 9360 with 7th or 8th gen Intel CPU?

> >>>>

> >>>> Hi Mario,

> >>>>

> >>>> I've got BIOS version 2.5.0 with the 7th gen Intel CPU.

> >>>>

> >>>>

> >>>> Regards,

> >>>> Jeremy

> >>>

> >>> Jeremy,

> >>>

> >>> Thanks.  Do you have any of the Dell docks (TB16/WD15)?  If so are you

> connected

> >> to any dock

> >>> when reproducing this problem?

> >>

> >> Mario,

> >>

> >> I do have a TB16. I can reproduce this whether or not I'm connected to

> >> the dock, though.

> >>

> >>

> >> Regards,

> >> Jeremy

> >

> > Jeremy,

> >

> > Can you try booting up from a cold boot with it connected to see if it still

> happens?

> >

> 

> Mario,

> 

> Yup, it still happens from a cold boot when connected to the dock.


OK thanks for confirming.  Here's what I've concluded:

* So looking through the ACPI tables on the 9360 it initializes that status
(slate vs laptop mode) bit to "slate" mode.  The 9360 isn't a 2-in1- so that
seems wrong to me, but that's what it does.
It only gets updated based on dock status.

The 9365 (which is a 2 in 1) however seems to initialize the status properly.

So that's an impasse of what to do.
It's not clear to me what is really happening:
a) We're missing something else in this driver (eg something else that 
indicates whether to trust VGBS output)

b) Mis-interpreting the results from it (we shouldn't report the switch for 
tablet mode based on what we do)

c) 9360 has a BIOS bug (seems unlikely since Windows doesn't freak out and
show virtual keyboard at wrong time)

I'm leaning on it's probably <a>.
We should check for tablet mode should only be run if chassis type 
matches 2-in-1 (chassis type 0x1F).  

I believe that should fix the problem on the 9360, let it continue to work on
the 9365 (and other 2-in-1's).

Can you guys please test this?  If that works I'll split up the routine and submit
it.

Comments

Jeremy Cline Feb. 22, 2018, 7:45 p.m. UTC | #1
On 02/22/2018 12:05 PM, Mario.Limonciello@dell.com wrote:
>> -----Original Message-----
>> From: platform-driver-x86-owner@vger.kernel.org [mailto:platform-driver-x86-
>> owner@vger.kernel.org] On Behalf Of Jeremy Cline
>> Sent: Thursday, February 22, 2018 10:42 AM
>> To: Limonciello, Mario <Mario_Limonciello@Dell.com>; notmart@gmail.com
>> Cc: pali.rohar@gmail.com; andriy.shevchenko@linux.intel.com;
>> mjg59@srcf.ucam.org; dvhart@infradead.org; platform-driver-
>> x86@vger.kernel.org; linux-kernel@vger.kernel.org
>> Subject: Re: Regression: Dell XPS 13 9360 keyboard no longer works
>>
>> On 02/22/2018 11:17 AM, Mario.Limonciello@dell.com wrote:
>>>> -----Original Message-----
>>>> From: platform-driver-x86-owner@vger.kernel.org [mailto:platform-driver-x86-
>>>> owner@vger.kernel.org] On Behalf Of Jeremy Cline
>>>> Sent: Thursday, February 22, 2018 10:17 AM
>>>> To: Limonciello, Mario <Mario_Limonciello@Dell.com>; notmart@gmail.com
>>>> Cc: pali.rohar@gmail.com; andriy.shevchenko@linux.intel.com;
>>>> mjg59@srcf.ucam.org; dvhart@infradead.org; platform-driver-
>>>> x86@vger.kernel.org; linux-kernel@vger.kernel.org
>>>> Subject: Re: Regression: Dell XPS 13 9360 keyboard no longer works
>>>>
>>>> On 02/22/2018 11:14 AM, Mario.Limonciello@dell.com wrote:
>>>>>> -----Original Message-----
>>>>>> From: Jeremy Cline [mailto:jeremy@jcline.org]
>>>>>> Sent: Thursday, February 22, 2018 9:59 AM
>>>>>> To: Limonciello, Mario <Mario_Limonciello@Dell.com>; notmart@gmail.com
>>>>>> Cc: pali.rohar@gmail.com; andriy.shevchenko@linux.intel.com;
>>>>>> mjg59@srcf.ucam.org; dvhart@infradead.org; platform-driver-
>>>>>> x86@vger.kernel.org; linux-kernel@vger.kernel.org
>>>>>> Subject: Re: Regression: Dell XPS 13 9360 keyboard no longer works
>>>>>>
>>>>>> On 02/22/2018 10:21 AM, Mario.Limonciello@dell.com wrote:> I guess that
>>>>>> means we got this wrong and the patch should be reverted
>>>>>>> until we figure this out.
>>>>>>>
>>>>>>> Jeremy,
>>>>>>>
>>>>>>> Can you please confirm what BIOS version you are on?
>>>>>>> Also Is this a 9360 with 7th or 8th gen Intel CPU?
>>>>>>
>>>>>> Hi Mario,
>>>>>>
>>>>>> I've got BIOS version 2.5.0 with the 7th gen Intel CPU.
>>>>>>
>>>>>>
>>>>>> Regards,
>>>>>> Jeremy
>>>>>
>>>>> Jeremy,
>>>>>
>>>>> Thanks.  Do you have any of the Dell docks (TB16/WD15)?  If so are you
>> connected
>>>> to any dock
>>>>> when reproducing this problem?
>>>>
>>>> Mario,
>>>>
>>>> I do have a TB16. I can reproduce this whether or not I'm connected to
>>>> the dock, though.
>>>>
>>>>
>>>> Regards,
>>>> Jeremy
>>>
>>> Jeremy,
>>>
>>> Can you try booting up from a cold boot with it connected to see if it still
>> happens?
>>>
>>
>> Mario,
>>
>> Yup, it still happens from a cold boot when connected to the dock.
> 
> OK thanks for confirming.  Here's what I've concluded:
> 
> * So looking through the ACPI tables on the 9360 it initializes that status
> (slate vs laptop mode) bit to "slate" mode.  The 9360 isn't a 2-in1- so that
> seems wrong to me, but that's what it does.
> It only gets updated based on dock status.
> 
> The 9365 (which is a 2 in 1) however seems to initialize the status properly.
> 
> So that's an impasse of what to do.
> It's not clear to me what is really happening:
> a) We're missing something else in this driver (eg something else that 
> indicates whether to trust VGBS output)
> 
> b) Mis-interpreting the results from it (we shouldn't report the switch for 
> tablet mode based on what we do)
> 
> c) 9360 has a BIOS bug (seems unlikely since Windows doesn't freak out and
> show virtual keyboard at wrong time)
> 
> I'm leaning on it's probably <a>.
> We should check for tablet mode should only be run if chassis type 
> matches 2-in-1 (chassis type 0x1F).  
> 
> I believe that should fix the problem on the 9360, let it continue to work on
> the 9365 (and other 2-in-1's).
> 
> Can you guys please test this?  If that works I'll split up the routine and submit
> it.
> 

Hi Mario,

There's one small error in the patch, after I fixed it, it works.
Thanks!

> diff --git a/drivers/platform/x86/intel-vbtn.c b/drivers/platform/x86/intel-vbtn.c
> index b703d6f..07bc489 100644
> --- a/drivers/platform/x86/intel-vbtn.c
> +++ b/drivers/platform/x86/intel-vbtn.c
> @@ -7,6 +7,7 @@
>   */
>  
>  #include <linux/acpi.h>
> +#include <linux/dmi.h>
>  #include <linux/input.h>
>  #include <linux/input/sparse-keymap.h>
>  #include <linux/kernel.h>
> @@ -102,6 +103,7 @@ static int intel_vbtn_probe(struct platform_device *device)
>         struct acpi_buffer vgbs_output = { ACPI_ALLOCATE_BUFFER, NULL };
>         acpi_handle handle = ACPI_HANDLE(&device->dev);
>         struct intel_vbtn_priv *priv;
> +       const char *chassis_type;
>         acpi_status status;
>         int err;
>  
> @@ -123,22 +125,24 @@ static int intel_vbtn_probe(struct platform_device *device)
>         }
>  
>         /*
> -        * VGBS being present and returning something means we have
> -        * a tablet mode switch.
> +        * Running on 2-in-1 chassis, VGBS being present and
> +        * returning something means we have a tablet mode switch.
>          */
> -       status = acpi_evaluate_object(handle, "VGBS", NULL, &vgbs_output);
> -       if (ACPI_SUCCESS(status)) {
> -               union acpi_object *obj = vgbs_output.pointer;
> +       chassis_type = dmi_get_system_info(DMI_CHASSIS_TYPE);
> +        if (chassis_type && strcmp(chassis_type, "31")) {This should be "chassis_type && strcmp(chassis_type, "31") == 0" since
strcmp returns 0 for equality.

> +               status = acpi_evaluate_object(handle, "VGBS", NULL, &vgbs_output);
> +               if (ACPI_SUCCESS(status)) {
> +                       union acpi_object *obj = vgbs_output.pointer;
>  
> -               if (obj && obj->type == ACPI_TYPE_INTEGER) {
> -                       int m = !(obj->integer.value & TABLET_MODE_FLAG);
> +                       if (obj && obj->type == ACPI_TYPE_INTEGER) {
> +                               int m = !(obj->integer.value & TABLET_MODE_FLAG);
>  
> -                       input_report_switch(priv->input_dev, SW_TABLET_MODE, m);
> +                               input_report_switch(priv->input_dev, SW_TABLET_MODE, m);
> +                       }
>                 }
> +               kfree(vgbs_output.pointer);
>         }
> -       kfree(vgbs_output.pointer);
> -
>         status = acpi_install_notify_handler(handle,
>                                              ACPI_DEVICE_NOTIFY,
>                                              notify_handler,
> 

Regards,
Jeremy
Darren Hart Feb. 22, 2018, 7:50 p.m. UTC | #2
On Thu, Feb 22, 2018 at 05:05:39PM +0000, Mario.Limonciello@dell.com wrote:
...
> OK thanks for confirming.  Here's what I've concluded:
> 
> * So looking through the ACPI tables on the 9360 it initializes that status
> (slate vs laptop mode) bit to "slate" mode.  The 9360 isn't a 2-in1- so that
> seems wrong to me, but that's what it does.
> It only gets updated based on dock status.
> 
> The 9365 (which is a 2 in 1) however seems to initialize the status properly.
> 
> So that's an impasse of what to do.
> It's not clear to me what is really happening:
> a) We're missing something else in this driver (eg something else that 
> indicates whether to trust VGBS output)
> 
> b) Mis-interpreting the results from it (we shouldn't report the switch for 
> tablet mode based on what we do)
> 
> c) 9360 has a BIOS bug (seems unlikely since Windows doesn't freak out and
> show virtual keyboard at wrong time)
> 
> I'm leaning on it's probably <a>.
> We should check for tablet mode should only be run if chassis type 
> matches 2-in-1 (chassis type 0x1F).  

This sounds like a good approach to me.

> I believe that should fix the problem on the 9360, let it continue to work on
> the 9365 (and other 2-in-1's).
> 
> Can you guys please test this?  If that works I'll split up the routine and submit
> it.

Queueing this up as well.
Limonciello, Mario Feb. 22, 2018, 8 p.m. UTC | #3
> -----Original Message-----

> From: platform-driver-x86-owner@vger.kernel.org [mailto:platform-driver-x86-

> owner@vger.kernel.org] On Behalf Of Jeremy Cline

> Sent: Thursday, February 22, 2018 1:45 PM

> To: Limonciello, Mario <Mario_Limonciello@Dell.com>; notmart@gmail.com

> Cc: pali.rohar@gmail.com; andriy.shevchenko@linux.intel.com;

> mjg59@srcf.ucam.org; dvhart@infradead.org; platform-driver-

> x86@vger.kernel.org; linux-kernel@vger.kernel.org

> Subject: Re: Regression: Dell XPS 13 9360 keyboard no longer works

> 

> On 02/22/2018 12:05 PM, Mario.Limonciello@dell.com wrote:

> >> -----Original Message-----

> >> From: platform-driver-x86-owner@vger.kernel.org [mailto:platform-driver-x86-

> >> owner@vger.kernel.org] On Behalf Of Jeremy Cline

> >> Sent: Thursday, February 22, 2018 10:42 AM

> >> To: Limonciello, Mario <Mario_Limonciello@Dell.com>; notmart@gmail.com

> >> Cc: pali.rohar@gmail.com; andriy.shevchenko@linux.intel.com;

> >> mjg59@srcf.ucam.org; dvhart@infradead.org; platform-driver-

> >> x86@vger.kernel.org; linux-kernel@vger.kernel.org

> >> Subject: Re: Regression: Dell XPS 13 9360 keyboard no longer works

> >>

> >> On 02/22/2018 11:17 AM, Mario.Limonciello@dell.com wrote:

> >>>> -----Original Message-----

> >>>> From: platform-driver-x86-owner@vger.kernel.org [mailto:platform-driver-

> x86-

> >>>> owner@vger.kernel.org] On Behalf Of Jeremy Cline

> >>>> Sent: Thursday, February 22, 2018 10:17 AM

> >>>> To: Limonciello, Mario <Mario_Limonciello@Dell.com>; notmart@gmail.com

> >>>> Cc: pali.rohar@gmail.com; andriy.shevchenko@linux.intel.com;

> >>>> mjg59@srcf.ucam.org; dvhart@infradead.org; platform-driver-

> >>>> x86@vger.kernel.org; linux-kernel@vger.kernel.org

> >>>> Subject: Re: Regression: Dell XPS 13 9360 keyboard no longer works

> >>>>

> >>>> On 02/22/2018 11:14 AM, Mario.Limonciello@dell.com wrote:

> >>>>>> -----Original Message-----

> >>>>>> From: Jeremy Cline [mailto:jeremy@jcline.org]

> >>>>>> Sent: Thursday, February 22, 2018 9:59 AM

> >>>>>> To: Limonciello, Mario <Mario_Limonciello@Dell.com>;

> notmart@gmail.com

> >>>>>> Cc: pali.rohar@gmail.com; andriy.shevchenko@linux.intel.com;

> >>>>>> mjg59@srcf.ucam.org; dvhart@infradead.org; platform-driver-

> >>>>>> x86@vger.kernel.org; linux-kernel@vger.kernel.org

> >>>>>> Subject: Re: Regression: Dell XPS 13 9360 keyboard no longer works

> >>>>>>

> >>>>>> On 02/22/2018 10:21 AM, Mario.Limonciello@dell.com wrote:> I guess

> that

> >>>>>> means we got this wrong and the patch should be reverted

> >>>>>>> until we figure this out.

> >>>>>>>

> >>>>>>> Jeremy,

> >>>>>>>

> >>>>>>> Can you please confirm what BIOS version you are on?

> >>>>>>> Also Is this a 9360 with 7th or 8th gen Intel CPU?

> >>>>>>

> >>>>>> Hi Mario,

> >>>>>>

> >>>>>> I've got BIOS version 2.5.0 with the 7th gen Intel CPU.

> >>>>>>

> >>>>>>

> >>>>>> Regards,

> >>>>>> Jeremy

> >>>>>

> >>>>> Jeremy,

> >>>>>

> >>>>> Thanks.  Do you have any of the Dell docks (TB16/WD15)?  If so are you

> >> connected

> >>>> to any dock

> >>>>> when reproducing this problem?

> >>>>

> >>>> Mario,

> >>>>

> >>>> I do have a TB16. I can reproduce this whether or not I'm connected to

> >>>> the dock, though.

> >>>>

> >>>>

> >>>> Regards,

> >>>> Jeremy

> >>>

> >>> Jeremy,

> >>>

> >>> Can you try booting up from a cold boot with it connected to see if it still

> >> happens?

> >>>

> >>

> >> Mario,

> >>

> >> Yup, it still happens from a cold boot when connected to the dock.

> >

> > OK thanks for confirming.  Here's what I've concluded:

> >

> > * So looking through the ACPI tables on the 9360 it initializes that status

> > (slate vs laptop mode) bit to "slate" mode.  The 9360 isn't a 2-in1- so that

> > seems wrong to me, but that's what it does.

> > It only gets updated based on dock status.

> >

> > The 9365 (which is a 2 in 1) however seems to initialize the status properly.

> >

> > So that's an impasse of what to do.

> > It's not clear to me what is really happening:

> > a) We're missing something else in this driver (eg something else that

> > indicates whether to trust VGBS output)

> >

> > b) Mis-interpreting the results from it (we shouldn't report the switch for

> > tablet mode based on what we do)

> >

> > c) 9360 has a BIOS bug (seems unlikely since Windows doesn't freak out and

> > show virtual keyboard at wrong time)

> >

> > I'm leaning on it's probably <a>.

> > We should check for tablet mode should only be run if chassis type

> > matches 2-in-1 (chassis type 0x1F).

> >

> > I believe that should fix the problem on the 9360, let it continue to work on

> > the 9365 (and other 2-in-1's).

> >

> > Can you guys please test this?  If that works I'll split up the routine and submit

> > it.

> >

> 

> Hi Mario,

> 

> There's one small error in the patch, after I fixed it, it works.

> Thanks!


Thanks, glad to hear.  I sent it to the list separately with my cleanups and your
fix for strcmp.

If you can re-test with the cleaned up patch to add a Tested-By, that would
be great.

> 

> > diff --git a/drivers/platform/x86/intel-vbtn.c b/drivers/platform/x86/intel-vbtn.c

> > index b703d6f..07bc489 100644

> > --- a/drivers/platform/x86/intel-vbtn.c

> > +++ b/drivers/platform/x86/intel-vbtn.c

> > @@ -7,6 +7,7 @@

> >   */

> >

> >  #include <linux/acpi.h>

> > +#include <linux/dmi.h>

> >  #include <linux/input.h>

> >  #include <linux/input/sparse-keymap.h>

> >  #include <linux/kernel.h>

> > @@ -102,6 +103,7 @@ static int intel_vbtn_probe(struct platform_device

> *device)

> >         struct acpi_buffer vgbs_output = { ACPI_ALLOCATE_BUFFER, NULL };

> >         acpi_handle handle = ACPI_HANDLE(&device->dev);

> >         struct intel_vbtn_priv *priv;

> > +       const char *chassis_type;

> >         acpi_status status;

> >         int err;

> >

> > @@ -123,22 +125,24 @@ static int intel_vbtn_probe(struct platform_device

> *device)

> >         }

> >

> >         /*

> > -        * VGBS being present and returning something means we have

> > -        * a tablet mode switch.

> > +        * Running on 2-in-1 chassis, VGBS being present and

> > +        * returning something means we have a tablet mode switch.

> >          */

> > -       status = acpi_evaluate_object(handle, "VGBS", NULL, &vgbs_output);

> > -       if (ACPI_SUCCESS(status)) {

> > -               union acpi_object *obj = vgbs_output.pointer;

> > +       chassis_type = dmi_get_system_info(DMI_CHASSIS_TYPE);

> > +        if (chassis_type && strcmp(chassis_type, "31")) {This should be

> "chassis_type && strcmp(chassis_type, "31") == 0" since

> strcmp returns 0 for equality.

> 

> > +               status = acpi_evaluate_object(handle, "VGBS", NULL, &vgbs_output);

> > +               if (ACPI_SUCCESS(status)) {

> > +                       union acpi_object *obj = vgbs_output.pointer;

> >

> > -               if (obj && obj->type == ACPI_TYPE_INTEGER) {

> > -                       int m = !(obj->integer.value & TABLET_MODE_FLAG);

> > +                       if (obj && obj->type == ACPI_TYPE_INTEGER) {

> > +                               int m = !(obj->integer.value & TABLET_MODE_FLAG);

> >

> > -                       input_report_switch(priv->input_dev, SW_TABLET_MODE, m);

> > +                               input_report_switch(priv->input_dev, SW_TABLET_MODE, m);

> > +                       }

> >                 }

> > +               kfree(vgbs_output.pointer);

> >         }

> > -       kfree(vgbs_output.pointer);

> > -

> >         status = acpi_install_notify_handler(handle,

> >                                              ACPI_DEVICE_NOTIFY,

> >                                              notify_handler,

> >

> 

> Regards,

> Jeremy
diff mbox

Patch

diff --git a/drivers/platform/x86/intel-vbtn.c b/drivers/platform/x86/intel-vbtn.c
index b703d6f..07bc489 100644
--- a/drivers/platform/x86/intel-vbtn.c
+++ b/drivers/platform/x86/intel-vbtn.c
@@ -7,6 +7,7 @@ 
  */
 
 #include <linux/acpi.h>
+#include <linux/dmi.h>
 #include <linux/input.h>
 #include <linux/input/sparse-keymap.h>
 #include <linux/kernel.h>
@@ -102,6 +103,7 @@  static int intel_vbtn_probe(struct platform_device *device)
        struct acpi_buffer vgbs_output = { ACPI_ALLOCATE_BUFFER, NULL };
        acpi_handle handle = ACPI_HANDLE(&device->dev);
        struct intel_vbtn_priv *priv;
+       const char *chassis_type;
        acpi_status status;
        int err;
 
@@ -123,22 +125,24 @@  static int intel_vbtn_probe(struct platform_device *device)
        }
 
        /*
-        * VGBS being present and returning something means we have
-        * a tablet mode switch.
+        * Running on 2-in-1 chassis, VGBS being present and
+        * returning something means we have a tablet mode switch.
         */
-       status = acpi_evaluate_object(handle, "VGBS", NULL, &vgbs_output);
-       if (ACPI_SUCCESS(status)) {
-               union acpi_object *obj = vgbs_output.pointer;
+       chassis_type = dmi_get_system_info(DMI_CHASSIS_TYPE);
+        if (chassis_type && strcmp(chassis_type, "31")) {
+               status = acpi_evaluate_object(handle, "VGBS", NULL, &vgbs_output);
+               if (ACPI_SUCCESS(status)) {
+                       union acpi_object *obj = vgbs_output.pointer;
 
-               if (obj && obj->type == ACPI_TYPE_INTEGER) {
-                       int m = !(obj->integer.value & TABLET_MODE_FLAG);
+                       if (obj && obj->type == ACPI_TYPE_INTEGER) {
+                               int m = !(obj->integer.value & TABLET_MODE_FLAG);
 
-                       input_report_switch(priv->input_dev, SW_TABLET_MODE, m);
+                               input_report_switch(priv->input_dev, SW_TABLET_MODE, m);
+                       }
                }
+               kfree(vgbs_output.pointer);
        }
-       kfree(vgbs_output.pointer);
-
        status = acpi_install_notify_handler(handle,
                                             ACPI_DEVICE_NOTIFY,
                                             notify_handler,