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Date:   Thu, 22 Feb 2018 20:15:51 +0000
From:   Jeremy Cline <jeremy@jcline.org>
To:     Mario Limonciello <mario.limonciello@dell.com>
Cc:     dvhart@infradead.org, Andy Shevchenko <andy.shevchenko@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        platform-driver-x86@vger.kernel.org,
        Alex Hung <alex.hung@canonical.com>
Subject: Re: [PATCH] platform/x86: Only activate tablet mode switch on
 2-in-1's
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On Thu, Feb 22, 2018 at 01:58:42PM -0600, Mario Limonciello wrote:
> Some laptops such as the XPS 9360 support the intel-vbtn INT33D6
> interface but don't initialize the bit that intel-vbtn uses to
> represent switching tablet mode.
> 
> By running this only on real 2-in-1's it shouldn't cause false
> positives.
> 
> Fixes: 30323fb6d5 ("Support tablet mode switch")
> Reported-by: Jeremy Cline <jeremy@jcline.org>
> Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
> ---
> Note: I also moved the code for detecting tablet into it's own
> function.  To keep things under 80 lines with if statements was
> making the code very unreadable otherwise.
> 
>  drivers/platform/x86/intel-vbtn.c | 46 ++++++++++++++++++++++++---------------
>  1 file changed, 29 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/platform/x86/intel-vbtn.c b/drivers/platform/x86/intel-vbtn.c
> index b703d6f..8173307 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>
> @@ -97,9 +98,35 @@ static void notify_handler(acpi_handle handle, u32 event, void *context)
>  	dev_dbg(&device->dev, "unknown event index 0x%x\n", event);
>  }
>  
> -static int intel_vbtn_probe(struct platform_device *device)
> +static void detect_tablet_mode(struct platform_device *device)
>  {
> +	const char *chassis_type = dmi_get_system_info(DMI_CHASSIS_TYPE);
> +	struct intel_vbtn_priv *priv = dev_get_drvdata(&device->dev);
> +	acpi_handle handle = ACPI_HANDLE(&device->dev);
>  	struct acpi_buffer vgbs_output = { ACPI_ALLOCATE_BUFFER, NULL };
> +	union acpi_object *obj;
> +	acpi_status status;
> +	int m;
> +
> +	if (!(chassis_type && strcmp(chassis_type, "31") == 0))
> +		goto out;
> +
> +	status = acpi_evaluate_object(handle, "VGBS", NULL, &vgbs_output);
> +	if (ACPI_FAILURE(status))
> +		goto out;
> +
> +	obj = vgbs_output.pointer;
> +	if (!(obj && obj->type == ACPI_TYPE_INTEGER))
> +		goto out;
> +
> +	m = !(obj->integer.value & TABLET_MODE_FLAG);
> +	input_report_switch(priv->input_dev, SW_TABLET_MODE, m);
> +out:
> +	kfree(vgbs_output.pointer);
> +}
> +
> +static int intel_vbtn_probe(struct platform_device *device)
> +{
>  	acpi_handle handle = ACPI_HANDLE(&device->dev);
>  	struct intel_vbtn_priv *priv;
>  	acpi_status status;
> @@ -122,22 +149,7 @@ static int intel_vbtn_probe(struct platform_device *device)
>  		return err;
>  	}
>  
> -	/*
> -	 * 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;
> -
> -		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);
> -		}
> -	}
> -
> -	kfree(vgbs_output.pointer);
> +	detect_tablet_mode(device);
>  
>  	status = acpi_install_notify_handler(handle,
>  					     ACPI_DEVICE_NOTIFY,
> -- 
> 2.7.4
> 

Tested-by: Jeremy Cline <jeremy@jcline.org>


Regards,
Jeremy