Re: [PATCH v2 2/4] platform/x86: thinkpad_acpi: Support for trackpoint doubletap

From: Mark Pearson
Date: Wed Apr 17 2024 - 19:57:51 EST


Hi Hans,

On Wed, Apr 17, 2024, at 4:06 PM, Hans de Goede wrote:
> Hi Mark,
>
> On 4/17/24 9:39 PM, Hans de Goede wrote:
>> Hi Mark,
>>
>> Thank you for the new version of this series, overall this looks good,
>> one small remark below.
>>
>> On 4/17/24 7:31 PM, Mark Pearson wrote:
>>> Lenovo trackpoints are adding the ability to generate a doubletap event.
>>> This handles the doubletap event and sends the KEY_PROG1 event to
>>> userspace.
>>>
>>> Signed-off-by: Mark Pearson <mpearson-lenovo@xxxxxxxxx>
>>> Signed-off-by: Vishnu Sankar <vishnuocv@xxxxxxxxx>
>>> ---
>>> Changes in v2:
>>> - Use KEY_PROG1 instead of KEY_DOUBLETAP as input maintainer doesn't
>>> want new un-specific key codes added.
>>> - Add doubletap to hotkey scan code table and use existing hotkey
>>> functionality.
>>> - Tested using evtest, and then gnome settings to configure a custom shortcut
>>> to launch an application.
>>>
>>> drivers/platform/x86/thinkpad_acpi.c | 18 ++++++++++++++++++
>>> 1 file changed, 18 insertions(+)
>>>
>>> diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
>>> index 3b48d893280f..6d04d45e8d45 100644
>>> --- a/drivers/platform/x86/thinkpad_acpi.c
>>> +++ b/drivers/platform/x86/thinkpad_acpi.c
>>> @@ -232,6 +232,9 @@ enum tpacpi_hkey_event_t {
>>>
>>> /* Misc */
>>> TP_HKEY_EV_RFKILL_CHANGED = 0x7000, /* rfkill switch changed */
>>> +
>>> + /* Misc2 */
>>> + TP_HKEY_EV_TRACK_DOUBLETAP = 0x8036, /* trackpoint doubletap */
>>> };
>>>
>>> /****************************************************************************
>>> @@ -1786,6 +1789,7 @@ enum { /* hot key scan codes (derived from ACPI DSDT) */
>>> TP_ACPI_HOTKEYSCAN_NOTIFICATION_CENTER,
>>> TP_ACPI_HOTKEYSCAN_PICKUP_PHONE,
>>> TP_ACPI_HOTKEYSCAN_HANGUP_PHONE,
>>
>> I understand why you've done this but I think this needs a comment,
>> something like:
>>
>> /*
>> * For TP_HKEY_EV_TRACK_DOUBLETAP, unlike the codes above which map to:
>> * (hkey_event - 0x1300) + TP_ACPI_HOTKEYSCAN_EXTENDED_START, this is
>> * hardcoded for TP_HKEY_EV_TRACK_DOUBLETAP handling. Therefor this must
>> * always be the last entry (after any 0x1300-0x13ff entries).
>> */
>> + TP_ACPI_HOTKEYSCAN_DOUBLETAP,
>
> Ugh, actually this will not work becuuse we want hotkeyscancodes to be stable
> because these are userspace API since they can be remapped using hwdb so we
> cannot have the hotkeyscancode changing when new 0x1300-0x13ff range entries
> get added.
>
> So we need to either grow the table a lot and reserve a whole bunch of space
> for future 0x13xx - 0x13ff codes or maybe something like this:
>
> diff --git a/drivers/platform/x86/thinkpad_acpi.c
> b/drivers/platform/x86/thinkpad_acpi.c
> index 771aaa7ae4cf..af3279889ecc 100644
> --- a/drivers/platform/x86/thinkpad_acpi.c
> +++ b/drivers/platform/x86/thinkpad_acpi.c
> @@ -1742,7 +1742,12 @@ enum { /* hot key scan codes (derived from ACPI
> DSDT) */
> TP_ACPI_HOTKEYSCAN_VOLUMEDOWN,
> TP_ACPI_HOTKEYSCAN_MUTE,
> TP_ACPI_HOTKEYSCAN_THINKPAD,
> - TP_ACPI_HOTKEYSCAN_UNK1,
> + /*
> + * Note this gets send both on 0x1019 and on
> TP_HKEY_EV_TRACK_DOUBLETAP
> + * hotkey-events. 0x1019 events have never been seen on any actual hw
> + * and a scancode is needed for the special 0x8036 doubletap
> hotkey-event.
> + */
> + TP_ACPI_HOTKEYSCAN_DOUBLETAP,
> TP_ACPI_HOTKEYSCAN_UNK2,
> TP_ACPI_HOTKEYSCAN_UNK3,
> TP_ACPI_HOTKEYSCAN_UNK4,
>
> or just hardcode KEY_PROG1 like your previous patch does, but I'm not
> a fan of that because of loosing hwdb remapping functionality for this
> "key" then.
>
> Note I'm open to other suggestions.
>
Oh...I hadn't thought of that impact. That's not great :(

I have an idea, but want to prototype it to see if it works out or not. Will update once I've had a chance to play with it.

Mark