linux-kernel - Re: [PATCH] Support intel-vbtn based tablet mode switch

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Date:   Mon, 22 Jan 2018 15:46:08 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Marco Martin <notmart@...il.com>
Cc:     linux-kernel@...r.kernel.org, mjg59@...f.ucam.org,
        pali.rohar@...il.com, dvhart@...radead.org, andy@...radead.org,
        bhush94@...il.com, platform-driver-x86@...r.kernel.org,
        mario.limonciello@...l.com,
        Mario Limonciello <mario_limonciello@...l.com>
Subject: Re: [PATCH] Support intel-vbtn based tablet mode switch

On Mon, Jan 22, 2018 at 01:48:01PM +0100, Marco Martin wrote:
> some laptops such as Dell Inspiron 7000 series have the
> tablet mode switch implemented in intel acpi,
> the events to enter and exit the tablet mode are 0xCC and 0xCD
> 
> CC: platform-driver-x86@...r.kernel.org
> CC: Matthew Garrett <mjg59@...f.ucam.org>
> CC: "Pali Rohár" <pali.rohar@...il.com>
> CC: Darren Hart <dvhart@...radead.org>
> CC: Mario Limonciello <mario_limonciello@...l.com>
> CC: Andy Shevchenko <andy@...radead.org>
> 
> Signed-off-by: Marco Martin <notmart@...il.com>
> ---
>  drivers/platform/x86/intel-vbtn.c | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
> 
> diff --git a/drivers/platform/x86/intel-vbtn.c b/drivers/platform/x86/intel-vbtn.c
> index 4809267..c4362df 100644
> --- a/drivers/platform/x86/intel-vbtn.c
> +++ b/drivers/platform/x86/intel-vbtn.c
> @@ -26,6 +26,9 @@
>  #include <linux/suspend.h>
>  #include <acpi/acpi_bus.h>
>  
> +/* When NOT in tablet mode, VBDS has the flag 0x40 */
> +#define TABLET_MODE_FLAG 0x40
> +
>  MODULE_LICENSE("GPL");
>  MODULE_AUTHOR("AceLan Kao");
>  
> @@ -42,6 +45,8 @@ static const struct key_entry intel_vbtn_keymap[] = {
>  	{ KE_IGNORE, 0xC5, { KEY_VOLUMEUP } },		/* volume-up key release */
>  	{ KE_KEY, 0xC6, { KEY_VOLUMEDOWN } },		/* volume-down key press */
>  	{ KE_IGNORE, 0xC7, { KEY_VOLUMEDOWN } },	/* volume-down key release */
> +	{ KE_SW,  0xCC, { .sw = { SW_TABLET_MODE, 1 } } }, /* Tabletmode in */
> +	{ KE_SW,  0xCD, { .sw = { SW_TABLET_MODE, 0 } } }, /* Tabletmode out */
>  	{ KE_END },
>  };
>  
> @@ -81,6 +86,7 @@ static void notify_handler(acpi_handle handle, u32 event, void *context)
>  			return;
>  		}
>  	} else if (sparse_keymap_report_event(priv->input_dev, event, 1, true)) {
> +		input_sync(priv->input_dev);

I do not understand why this is needed, as sparse keymap should issue
sync for you. From sparse_keymap_report_entry():

	case KE_SW:
		value = ke->sw.value;
		/* fall through */

	case KE_VSW:
		input_report_switch(dev, ke->sw.code, value);
		input_sync(dev);

		^^^^^^^^^- here is the sync.

		break;
	}
}

>  		return;
>  	}
>  	dev_info(&device->dev, "unknown event index 0x%x\n", event);
> @@ -92,6 +98,7 @@ static int intel_vbtn_probe(struct platform_device *device)
>  	struct intel_vbtn_priv *priv;
>  	acpi_status status;
>  	int err;
> +	struct acpi_buffer vgbs_output = { ACPI_ALLOCATE_BUFFER, NULL };
>  
>  	status = acpi_evaluate_object(handle, "VBDL", NULL, NULL);
>  	if (ACPI_FAILURE(status)) {
> @@ -110,6 +117,27 @@ static int intel_vbtn_probe(struct platform_device *device)
>  		return err;
>  	}
>  
> +	status = acpi_evaluate_object(handle, "VGBS", NULL, &vgbs_output);
> +	/* VGBS being present and returning something means
> +	 * we have a tablet mode switch
> +	 */
> +	if (ACPI_SUCCESS(status)) {
> +		union acpi_object *obj = vgbs_output.pointer;
> +
> +		input_set_capability(priv->input_dev, EV_SW, SW_TABLET_MODE);
> +
> +		if (obj && obj->type == ACPI_TYPE_INTEGER) {

Do you want to set the capability if you do not get 'obj' or it is of
different type?

> +			if (obj->integer.value & TABLET_MODE_FLAG)
> +				input_report_switch(priv->input_dev,
> +							SW_TABLET_MODE,
> +							0);
> +			else
> +				input_report_switch(priv->input_dev,
> +							SW_TABLET_MODE,
> +							1);

Can be shorter:

			input_report_switch(priv->input_dev, SW_TABLET_MODE,
					obj->integer.value & TABLET_MODE_FLAG);

You also need:

			input_sync(priv->input_dev);

Thanks.

-- 
Dmitry