Re: [PATCH v3 1/2] intel-hid: add support for SW_TABLET_MODE

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 12/4/20 5:01 PM, Elia Devito wrote:
> From: Elia Devito <eliadevito@gmail.com>
> 
> Some convertible use the intel-hid ACPI interface to report SW_TABLET_MODE,
> implement this with DMI based allow-list to be sure to activate support
> only on models that effectively have it.
> 
> Signed-off-by: Elia Devito <eliadevito@gmail.com>

Thank you for your patch-series.

Note there is one special corner-case which you missed wrt the
dynamic creation of the device on receiving 0xcc/0xcd events
(so patch 2/2). I've prepared a follow-up patch fixing this,
which I will post right after sending this email. The commit
msg of that patch gives more details.

I've applied the series to my review-hans branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans

Note it will show up in my review-hans branch once I've pushed my
local branch there, which might take a while.

Once I've run some tests on this branch the patches there will be
added to the platform-drivers-x86/for-next branch and eventually
will be included in the pdx86 pull-request to Linus for the next
merge-window.

Regards,

Hans

> ---
> v2:
>  patch reworked according to received feedbacks
>   
> v3:
>  improved code according to received feedbacks
> 
>  drivers/platform/x86/intel-hid.c | 95 ++++++++++++++++++++++++++++++++
>  1 file changed, 95 insertions(+)
> 
> diff --git a/drivers/platform/x86/intel-hid.c b/drivers/platform/x86/intel-hid.c
> index 86261970bd8f..d2f892665ec6 100644
> --- a/drivers/platform/x86/intel-hid.c
> +++ b/drivers/platform/x86/intel-hid.c
> @@ -15,6 +15,9 @@
>  #include <linux/platform_device.h>
>  #include <linux/suspend.h>
>  
> +/* When NOT in tablet mode, VGBS returns with the flag 0x40 */
> +#define TABLET_MODE_FLAG BIT(6)
> +
>  MODULE_LICENSE("GPL");
>  MODULE_AUTHOR("Alex Hung");
>  
> @@ -89,9 +92,26 @@ static const struct dmi_system_id button_array_table[] = {
>  	{ }
>  };
>  
> +/*
> + * Some convertible use the intel-hid ACPI interface to report SW_TABLET_MODE,
> + * these need to be compared via a DMI based authorization list because some
> + * models have unreliable VGBS return which could cause incorrect
> + * SW_TABLET_MODE report.
> + */
> +static const struct dmi_system_id dmi_vgbs_allow_list[] = {
> +	{
> +		.matches = {
> +			DMI_MATCH(DMI_SYS_VENDOR, "HP"),
> +			DMI_MATCH(DMI_PRODUCT_NAME, "HP Spectre x360 Convertible 15-df0xxx"),
> +		},
> +	},
> +	{ }
> +};
> +
>  struct intel_hid_priv {
>  	struct input_dev *input_dev;
>  	struct input_dev *array;
> +	struct input_dev *switches;
>  	bool wakeup_mode;
>  };
>  
> @@ -347,6 +367,57 @@ static int intel_button_array_input_setup(struct platform_device *device)
>  	return input_register_device(priv->array);
>  }
>  
> +static int intel_hid_switches_setup(struct platform_device *device)
> +{
> +	struct intel_hid_priv *priv = dev_get_drvdata(&device->dev);
> +
> +	/* Setup input device for switches */
> +	priv->switches = devm_input_allocate_device(&device->dev);
> +	if (!priv->switches)
> +		return -ENOMEM;
> +
> +	__set_bit(EV_SW, priv->switches->evbit);
> +	__set_bit(SW_TABLET_MODE, priv->switches->swbit);
> +
> +	priv->switches->name = "Intel HID switches";
> +	priv->switches->id.bustype = BUS_HOST;
> +	return input_register_device(priv->switches);
> +}
> +
> +static void report_tablet_mode_state(struct platform_device *device)
> +{
> +	struct intel_hid_priv *priv = dev_get_drvdata(&device->dev);
> +	acpi_handle handle = ACPI_HANDLE(&device->dev);
> +	unsigned long long vgbs;
> +	int m;
> +
> +	if (!intel_hid_evaluate_method(handle, INTEL_HID_DSM_VGBS_FN, &vgbs))
> +		return;
> +
> +	m = !(vgbs & TABLET_MODE_FLAG);
> +	input_report_switch(priv->switches, SW_TABLET_MODE, m);
> +	input_sync(priv->switches);
> +}
> +
> +static bool report_tablet_mode_event(struct input_dev *input_dev, u32 event)
> +{
> +	if (!input_dev)
> +		return false;
> +
> +	switch (event) {
> +	case 0xcc:
> +		input_report_switch(input_dev, SW_TABLET_MODE, 1);
> +		input_sync(input_dev);
> +		return true;
> +	case 0xcd:
> +		input_report_switch(input_dev, SW_TABLET_MODE, 0);
> +		input_sync(input_dev);
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
>  static void notify_handler(acpi_handle handle, u32 event, void *context)
>  {
>  	struct platform_device *device = context;
> @@ -363,6 +434,13 @@ static void notify_handler(acpi_handle handle, u32 event, void *context)
>  		if (event == 0xce)
>  			goto wakeup;
>  
> +		/*
> +		 * Switch events will wake the device and report the new switch
> +		 * position to the input subsystem.
> +		 */
> +		if (priv->switches && (event == 0xcc || event == 0xcd))
> +			goto wakeup;
> +
>  		/* Wake up on 5-button array events only. */
>  		if (event == 0xc0 || !priv->array)
>  			return;
> @@ -374,6 +452,10 @@ static void notify_handler(acpi_handle handle, u32 event, void *context)
>  
>  wakeup:
>  		pm_wakeup_hard_event(&device->dev);
> +
> +		if (report_tablet_mode_event(priv->switches, event))
> +			return;
> +
>  		return;
>  	}
>  
> @@ -398,6 +480,9 @@ static void notify_handler(acpi_handle handle, u32 event, void *context)
>  		}
>  	}
>  
> +	if (report_tablet_mode_event(priv->switches, event))
> +		return;
> +
>  	/* 0xC0 is for HID events, other values are for 5 button array */
>  	if (event != 0xc0) {
>  		if (!priv->array ||
> @@ -485,6 +570,16 @@ static int intel_hid_probe(struct platform_device *device)
>  			pr_err("Failed to setup Intel 5 button array hotkeys\n");
>  	}
>  
> +	/* Setup switches for devices that we know VGBS return correctly */
> +	if (dmi_check_system(dmi_vgbs_allow_list)) {
> +		dev_info(&device->dev, "platform supports switches\n");
> +		err = intel_hid_switches_setup(device);
> +		if (err)
> +			pr_err("Failed to setup Intel HID switches\n");
> +		else
> +			report_tablet_mode_state(device);
> +	}
> +
>  	status = acpi_install_notify_handler(handle,
>  					     ACPI_DEVICE_NOTIFY,
>  					     notify_handler,
>