Re: [PATCH] Process tablet mode events on Dell Inspiron 2n1

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

Hi,

Overall this patch looks good, I have 2 remarks:

1. Your commit message needs some work, the first line (Subject) should
briefly describe the change with a subsystem prefix, so something like this:

platform/x86: dell-wmi: Add SW_TABLET_MODE support for Dell Inspiron 2in1

And then an empty line followed by a "body" with a bit more detailed description.

And last but not least you need to add a Signed-off-by line like this:

Singed-off-by: Troy Rollo <linux2021@troy.rollo.name>

Which indicates that you authored the patch and are submitting it under
the standard kernel license, see:
https://elinux.org/Developer_Certificate_Of_Origin

2. Also have 1 remark about the code, see below.


On 9/9/21 5:35 AM, Troy Rollo wrote:
> ---
>  drivers/platform/x86/dell/dell-wmi-base.c | 36 ++++++++++++++++-------
>  1 file changed, 26 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/platform/x86/dell/dell-wmi-base.c b/drivers/platform/x86/dell/dell-wmi-base.c
> index 089c125e18f7..474ca05055ab 100644
> --- a/drivers/platform/x86/dell/dell-wmi-base.c
> +++ b/drivers/platform/x86/dell/dell-wmi-base.c
> @@ -309,6 +309,9 @@ static const struct key_entry dell_wmi_keymap_type_0010[] = {
>   * Keymap for WMI events of type 0x0011
>   */
>  static const struct key_entry dell_wmi_keymap_type_0011[] = {
> +	/* Reflex keyboard switch on 2n1 devices */
> +	{ KE_VSW,    0xe070, { .sw  = { SW_TABLET_MODE } } },
> +

By adding this here, any device loading the dell-wmi driver will now advertise
that it supports SW_TABLET_MODE reporting, even when it does not. This will
cause e.g. GNOME40 to disable accelerometer based rotation since when
SW_TABLET_MODE=0 is being reported then GNOME40 assumes it is running on a
2in1 in laptop mode and thus disable auto-rotation (and also the on-screen-kbd).

So advertising a non functional (always reporting 0) SW_TABLET_MODE switch
is harmful and this change will do this.

Since you already have special handling for the tablet-mode WMI events,
it would be better to use a separate input-device which just reports
SW_TABLET_MODE and which gets dynamically created upon receiving the
first 0x0011 0xe070 event. See the
drivers/platform/x86/intel/vbtn.c
drivers/platform/x86/intel/hid.c

Drivers for an example of 2 drivers already doing this.

Regards,

Hans



>  	/* Battery unplugged */
>  	{ KE_IGNORE, 0xfff0, { KEY_RESERVED } },
>  
> @@ -344,17 +347,19 @@ static const struct key_entry dell_wmi_keymap_type_0012[] = {
>  	{ KE_IGNORE, 0xe035, { KEY_RESERVED } },
>  };
>  
> -static void dell_wmi_process_key(struct wmi_device *wdev, int type, int code)
> +static int dell_wmi_process_key(struct wmi_device *wdev, int type, int code, u16 *buffer, int remaining)
>  {
>  	struct dell_wmi_priv *priv = dev_get_drvdata(&wdev->dev);
>  	const struct key_entry *key;
> +	int used = 0;
> +	int value = 1;
>  
>  	key = sparse_keymap_entry_from_scancode(priv->input_dev,
>  						(type << 16) | code);
>  	if (!key) {
>  		pr_info("Unknown key with type 0x%04x and code 0x%04x pressed\n",
>  			type, code);
> -		return;
> +		return 0;
>  	}
>  
>  	pr_debug("Key with type 0x%04x and code 0x%04x pressed\n", type, code);
> @@ -363,16 +368,22 @@ static void dell_wmi_process_key(struct wmi_device *wdev, int type, int code)
>  	if ((key->keycode == KEY_BRIGHTNESSUP ||
>  	     key->keycode == KEY_BRIGHTNESSDOWN) &&
>  	    acpi_video_handles_brightness_key_presses())
> -		return;
> +		return 0;
>  
>  	if (type == 0x0000 && code == 0xe025 && !wmi_requires_smbios_request)
> -		return;
> +		return 0;
>  
> -	if (key->keycode == KEY_KBDILLUMTOGGLE)
> +	if (key->keycode == KEY_KBDILLUMTOGGLE) {
>  		dell_laptop_call_notifier(
>  			DELL_LAPTOP_KBD_BACKLIGHT_BRIGHTNESS_CHANGED, NULL);
> +	} else if (type == 0x0011 && code == 0xe070 && remaining > 0) {
> +		value = !buffer[0];
> +		used = 1;
> +	}
> +
> +	sparse_keymap_report_entry(priv->input_dev, key, value, true);
>  
> -	sparse_keymap_report_entry(priv->input_dev, key, 1, true);
> +	return used;
>  }
>  
>  static void dell_wmi_notify(struct wmi_device *wdev,
> @@ -430,21 +441,26 @@ static void dell_wmi_notify(struct wmi_device *wdev,
>  		case 0x0000: /* One key pressed or event occurred */
>  			if (len > 2)
>  				dell_wmi_process_key(wdev, buffer_entry[1],
> -						     buffer_entry[2]);
> +						     buffer_entry[2],
> +						     buffer_entry + 3,
> +						     len - 3);
>  			/* Extended data is currently ignored */
>  			break;
>  		case 0x0010: /* Sequence of keys pressed */
>  		case 0x0011: /* Sequence of events occurred */
>  			for (i = 2; i < len; ++i)
> -				dell_wmi_process_key(wdev, buffer_entry[1],
> -						     buffer_entry[i]);
> +				i += dell_wmi_process_key(wdev, buffer_entry[1],
> +							  buffer_entry[i],
> +							  buffer_entry + i,
> +							  len - i - 1);
>  			break;
>  		case 0x0012:
>  			if ((len > 4) && dell_privacy_process_event(buffer_entry[1], buffer_entry[3],
>  								    buffer_entry[4]))
>  				/* dell_privacy_process_event has handled the event */;
>  			else if (len > 2)
> -				dell_wmi_process_key(wdev, buffer_entry[1], buffer_entry[2]);
> +				dell_wmi_process_key(wdev, buffer_entry[1], buffer_entry[2],
> +						     buffer_entry + 3, len - 3);
>  			break;
>  		default: /* Unknown event */
>  			pr_info("Unknown WMI event type 0x%x\n",
>