linux-kernel - Re: [PATCH 1/2] Input: Add a helper for reporting a screen lock key sequence

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Message-ID: <cebf59f2-5d81-41f9-8c4f-d51fcb514f86@kernel.org>
Date: Wed, 16 Apr 2025 15:43:26 -0500
From: Mario Limonciello <superm1@...nel.org>
To: Armin Wolf <W_Armin@....de>, Dmitry Torokhov <dmitry.torokhov@...il.com>,
 Shyam Sundar S K <Shyam-sundar.S-k@....com>,
 Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: Hans de Goede <hdegoede@...hat.com>,
 "open list:INPUT (KEYBOARD, MOUSE, JOYSTICK, TOUCHSCREEN)..."
 <linux-input@...r.kernel.org>, open list <linux-kernel@...r.kernel.org>,
 "open list:AMD PMF DRIVER" <platform-driver-x86@...r.kernel.org>,
 Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCH 1/2] Input: Add a helper for reporting a screen lock key
 sequence

On 4/16/2025 3:39 PM, Armin Wolf wrote:
> Am 07.04.25 um 17:27 schrieb Mario Limonciello:
> 
>> From: Mario Limonciello <mario.limonciello@....com>
>>
>> In the PC industry KEY_SCREENLOCK isn't used as frequently as it used
>> to be. Modern versions of Windows [1], GNOME and KDE support "META" + "L"
>> to lock the screen. Modern hardware [2] also sends this sequence of
>> events for keys with a silkscreen for screen lock.
>>
>> Introduced a helper input_report_lock_sequence() for drivers to utilize
>> if they want to send this sequence.
>>
>> Link: https://support.microsoft.com/en-us/windows/keyboard-shortcuts- 
>> in-windows-dcc61a57-8ff0-cffe-9796-cb9706c75eec [1]
>> Link: https://www.logitech.com/en-us/shop/p/k860-split- 
>> ergonomic.920-009166 [2]
>> Suggested-by: Armin Wolf <W_Armin@....de>
>> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
>> ---
>>   drivers/input/input.c | 20 ++++++++++++++++++++
>>   include/linux/input.h |  2 ++
>>   2 files changed, 22 insertions(+)
>>
>> diff --git a/drivers/input/input.c b/drivers/input/input.c
>> index ec4346f20efdd..dfeace85c4710 100644
>> --- a/drivers/input/input.c
>> +++ b/drivers/input/input.c
>> @@ -508,6 +508,26 @@ void input_copy_abs(struct input_dev *dst, 
>> unsigned int dst_axis,
>>   }
>>   EXPORT_SYMBOL(input_copy_abs);
>> +/**
>> + * input_report_lock_sequence - Report key combination to lock the 
>> screen
>> + * @dev: input device
>> + *
>> + * Key combination used in the PC industry since Windows 7 for 
>> locking display
>> + * is META + L. This is also used in GNOME and KDE by default.
>> + * See https://support.microsoft.com/en-us/windows/keyboard- 
>> shortcuts-in-windows-dcc61a57-8ff0-cffe-9796-cb9706c75eec
>> + */
> 
> Hi,
> 
> maybe it would make more sense to have the input subsystem transparently 
> translate between KEY_SCREENLOCK and this
> special screen lock sequence. This way there would be no room for 
> regressions as people could enable/disable this
> behavior via Kconfig.

Wouldn't all drivers that emit KEY_SCREENLOCK still need to be modified 
to have support to emit KEY_LEFTMETA and KEY_L?

Wouldn't that mean conditional code in every single driver based on the 
Kconfig?

Is that worth it?

> 
> Thanks,
> Armin Wolf
> 
>> +void input_report_lock_sequence(struct input_dev *dev)
>> +{
>> +    input_report_key(dev, KEY_LEFTMETA, 1);
>> +    input_report_key(dev, KEY_L, 1);
>> +    input_sync(dev);
>> +    input_report_key(dev, KEY_L, 0);
>> +    input_sync(dev);
>> +    input_report_key(dev, KEY_LEFTMETA, 0);
>> +    input_sync(dev);
>> +}
>> +EXPORT_SYMBOL(input_report_lock_sequence);
>> +
>>   /**
>>    * input_grab_device - grabs device for exclusive use
>>    * @handle: input handle that wants to own the device
>> diff --git a/include/linux/input.h b/include/linux/input.h
>> index 7d7cb0593a63e..16f7bef12f1c1 100644
>> --- a/include/linux/input.h
>> +++ b/include/linux/input.h
>> @@ -492,6 +492,8 @@ void input_set_abs_params(struct input_dev *dev, 
>> unsigned int axis,
>>   void input_copy_abs(struct input_dev *dst, unsigned int dst_axis,
>>               const struct input_dev *src, unsigned int src_axis);
>> +void input_report_lock_sequence(struct input_dev *dev);
>> +
>>   #define INPUT_GENERATE_ABS_ACCESSORS(_suffix, _item)            \
>>   static inline int input_abs_get_##_suffix(struct input_dev *dev,    \
>>                         unsigned int axis)        \