linux-kernel - Re: [PATCH 2/4] platform/x86: thinkpad_acpi: Support for trackpoint doubletap

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Message-ID: <e1ccf281-5c77-4447-a6c7-5b0b008c7c56@redhat.com>
Date: Mon, 8 Apr 2024 15:04:13 +0200
From: Hans de Goede <hdegoede@...hat.com>
To: Mark Pearson <mpearson-lenovo@...ebb.ca>
Cc: ilpo.jarvinen@...ux.intel.com, hmh@....eng.br, dmitry.torokhov@...il.com,
 ibm-acpi-devel@...ts.sourceforge.net, platform-driver-x86@...r.kernel.org,
 linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
 njoshi1@...ovo.com, vsankar@...ovo.com, peter.hutterer@...hat.com
Subject: Re: [PATCH 2/4] platform/x86: thinkpad_acpi: Support for trackpoint
 doubletap

Hi Mark,

On 3/24/24 10:07 PM, Mark Pearson wrote:
> Lenovo trackpoints are adding the ability to generate a doubletap event.
> This handles the doubletap event and sends the KEY_DOUBLECLICK event to
> userspace.
> 
> Signed-off-by: Mark Pearson <mpearson-lenovo@...ebb.ca>
> Signed-off-by: Vishnu Sankar <vsankar@...ovo.com>
> ---
>  drivers/platform/x86/thinkpad_acpi.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
> index 82429e59999d..2bbb32c898e9 100644
> --- a/drivers/platform/x86/thinkpad_acpi.c
> +++ b/drivers/platform/x86/thinkpad_acpi.c
> @@ -232,6 +232,7 @@ enum tpacpi_hkey_event_t {
>  
>  	/* Misc */
>  	TP_HKEY_EV_RFKILL_CHANGED	= 0x7000, /* rfkill switch changed */
> +	TP_HKEY_EV_TRACKPOINT_DOUBLETAP = 0x8036, /* doubletap on Trackpoint*/
>  };
>  
>  /****************************************************************************
> @@ -4081,6 +4082,22 @@ static void hotkey_notify(struct ibm_struct *ibm, u32 event)
>  				break;
>  			}
>  			fallthrough;	/* to default */

This now no longer fallsthrough to default. IMHO the best thing to do
here is add a new preparation patch which initializes known_ev to false
inside the while before the switch-case (together with the send_acpi_ev
and ignore_acpi_ev init). and then change this fallthrough to a break
in the preparation patch. You can then also remove the default case
altogether in this prep patch.

> +		case 8:
> +			/* 0x8036: Trackpoint doubletaps */
> +			if (hkey == TP_HKEY_EV_TRACKPOINT_DOUBLETAP) {
> +				send_acpi_ev = true;
> +				ignore_acpi_ev = false;

These 2 values are set as the default above the switch-case, please
drop these 2 lines.

> +				known_ev = true;
> +				/* Send to user space */
> +				mutex_lock(&tpacpi_inputdev_send_mutex);
> +				input_report_key(tpacpi_inputdev, KEY_DOUBLECLICK, 1);
> +				input_sync(tpacpi_inputdev);
> +				input_report_key(tpacpi_inputdev, KEY_DOUBLECLICK, 0);
> +				input_sync(tpacpi_inputdev);
> +				mutex_unlock(&tpacpi_inputdev_send_mutex);

This code duplicates tpacpi_input_send_key(), what you want to do here
is define a hotkey_keycode_map scancode range for new 0x8xxx codes like how this
was done when extended scancodes where added to deal with the new 0x13xx hotkey
event codes for the 2017+ models.

See commit 696c6523ec8f ("platform/x86: thinkpad_acpi: add mapping for new hotkeys")

Despite re-using tpacpi_input_send_key() there are 2 reasons why we want
scancodes for these new "keys".

1. By adding the keys to the hotkey_keycode_map they automatically
also get input_set_capability(tpacpi_inputdev, EV_KEY, hotkey_keycode_map[i]);
called on them advertising to userspace that tpacpi_inputdev can actually
generate these keypresses. Something which is currently lacking from your
patch. Related to this did you test this with evtest? I think that the input
core will suppress the events when you do not set the capability ?

2. This allows remapping scancodes to different KEY_foo values with hwdb
entries.

Regards,

Hans

> +				break;
> +			}
> +			fallthrough;	/* to default */
>  		default:
>  			known_ev = false;
>  		}