Re: [PATCH v2] platform/x86: ideapad-laptop: Report camera switch as SW_CAMERA_LENS_COVER

[Rong Zhang]

Hi Macro,

On Sun, 2026-09-20 at 22:28 +0200, Marco Giunta wrote:
> On certain 2025 Lenovo laptops, such as the Yoga Pro 7 14ASP10 and Legion
> Pro 7 16AFR10H, a switch on the side disables the camera. This is handled
> by the firmware, which also sends event 0x0d (camera disabled) or 0x0c
> (camera enabled) through the WMI event GUID handled with
> ideapad_wmi_context_fn_keys. These events are currently reported as
> KEY_UNKNOWN.
> 
> Other Lenovo laptops expose a similar camera switch through a separate WMI
> GUID, which lenovo-wmi-camera reports as SW_CAMERA_LENS_COVER since
> commit d98bf6a6ed61 ("platform/x86: lenovo-wmi-camera: Use
> SW_CAMERA_LENS_COVER instead of KEY_CAMERA_ACESS"). That driver does not
> bind on these laptops, so do the same here: as the switch state cannot be
> read from the firmware, register a separate input device with the switch
> on the first event, and report the state carried by each event.
> 
> Signed-off-by: Marco Giunta <marco_giunta@xxxxxxxxxx>
> ---
> Changes in v2:
> 
> * Add lockdep_assert_held(&ideapad_shared_mutex) and a comment at the top
>   of ideapad_camera_switch_report() to document and check that the WMI
>   notify path is serialized through ideapad_shared_mutex (suggested by
>   Huang Wei)
> * Replace dev_warn() with dev_warn_once() in
>   ideapad_camera_switch_report() so that a persistent registration failure
>   does not log a warning on every toggle (suggested by Huang Wei)
> 
> Link to v1: https://lore.kernel.org/platform-driver-x86/SN6PR19MB23039910DD1918BEE3825BAFFC862@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
> 
> Notes (copied verbatim from v1, to keep the context easily accessible):
> 
> * I considered a couple of alternatives to the approach in this patch:
> 
>   1.  Simply map 0x0c and 0x0d to KEY_CAMERA_ACCESS_ENABLE/DISABLE:
> 
>       { KE_KEY,	0x0c | IDEAPAD_WMI_KEY, { KEY_CAMERA_ACCESS_ENABLE } },
>       { KE_KEY,	0x0d | IDEAPAD_WMI_KEY, { KEY_CAMERA_ACCESS_DISABLE } },
> 
>       similar to the touchpad off/on hkey events (66/67) this driver emits
>       after the firmware has toggled the touchpad state. However, HUTRR72
>       describes these hkey events as asserting a camera access state for
>       the host to apply, rather than reporting one the firmware has
>       already applied. 
> 

Well, it really doesn't matter how the specification says; what matters
is how devices in reality do: whenever the HID Usage Table doesn't define
a usage for hardware/firmware to report the already-applied value but
defines a usage for notifying the host to apply a specific value, a lot
of devices will emerge, using the latter even when the former is
intended.

For example, many USB Audio Class devices come with volume control
buttons or knobs. Some of them tune the volume themselves as well as
emitting Volume Increment/Decrement HID events.

In this case, the audio stack, in response to the HID events,
intentionally overrides the volume set by hardware, effectively
synchronizing the hardware and software volume value.

The pattern has become so common that many devices like that also
implement an internal timeout mechanism. They only set the volume
themselves when reaching the timeout with no UAC volume control request
received.

IOW, it doesn't matter whether the hardware/firmware has done its job as
long as the subsequent software control is harmless. That's why we can
safely use KEY_TOUCHPAD_ON/OFF even if the firmware has toggled the
touchpad state. They cause the desktop environment to mask/unmask
touchpad input, which is essentially a no-op (thus a safe operation) when
the firmware has already disabled/enabled the touchpad.

Fundamentally speaking, using KEY_CAMERA_ACCESS_ENABLE/DISABLE is also
OK. It's just...

> Furthermore, lenovo-wmi-camera moved away from
>       these hkey events in favor of SW_CAMERA_LENS_COVER in the quoted
>       commit, which is arguably the closest relevant precedent.

...relatively new and isn't widely used compared to SW_CAMERA_LENS_COVER.

Thus, I agreed that using SW_CAMERA_LENS_COVER is a better approach as it
aligns with other drivers' behavior. The patch seems over-engineered
though, see below.

>     
>   2.  Ignore these events like the firmware-handled FnLock events:
> 
> 			{ KE_IGNORE,	0x0c | IDEAPAD_WMI_KEY },
> 			{ KE_IGNORE,	0x0d | IDEAPAD_WMI_KEY },
> 
>       This fixes the KEY_UNKNOWN issue, but userspace gets no information.
>     
>   Overall, in the end I copied the approach of the lenovo-wmi-camera
>   driver. Kindly let me know if there are other/better solutions.
>     
> * Unlike the touchpad, whose state this driver reads with VPCCMD_R_TOUCHPAD
>   at probe, on resume and on each event, 
> 

At least for the input device, the synchronization on probe or on resume
does not matter, as no input event is emitted due to !send_events.

> the camera switch state is only
>   available in EC-private fields, and the two tested laptops even use
>   different ones. Hence the lenovo-wmi-camera approach: the switch appears
>   on the first event, and a change made while suspended is not reported,
>   leaving the state wrong until the switch is toggled again.

So the difference compared to the lenovo-wmi-camera approach is only
about when and how the input device is registered.

On recent models, the firmware neither emits VPCCMD_R_TOUCHPAD nor
toggles the touchpad. It leaves the job to software by emitting WMI key
event 0x29, which is converted to KEY_TOUCHPAD_TOGGLE via ideapad_keymap.
It'd be tidier to take that approach and reuse the existing input device.
Sparse keymap supports KEY_SW, so it's viable to map the two WMI events
to SW_CAMERA_LENS_COVER with appropriate switch value.

I've attached a patch implementing the approach. Could you test if it
works on your devices? If so, you may submit my patch yourself by adding
a From: pseudo header with my identity and swapping the two Signed-off-
by: tags. I can also submit it myself as long as you permit me to do so.

> 
> * For reference, on KDE Plasma 6.7.5, using the Legion's touchpad toggle
>   button shows an OSD, but nothing on a SW_CAMERA_LENS_COVER change or if
>   sending KEY_CAMERA_ACCESS_ENABLE/DISABLE events. I am not sure whether
>   this is simply a case of "not implemented yet" or if I misunderstood how
>   these events are supposed to be used to communicate with userspace.
>   Please feel free to correct me here.

I believe KDE Plasma has not implemented it yet. You may raise an issue
on their Bugzilla.

Thanks,
Rong

>   
> Best regards,
> Marco
> ---
>  drivers/platform/x86/lenovo/ideapad-laptop.c | 59 ++++++++++++++++++++
>  1 file changed, 59 insertions(+)
> 
> diff --git a/drivers/platform/x86/lenovo/ideapad-laptop.c b/drivers/platform/x86/lenovo/ideapad-laptop.c
> index 207368f5d489..0066638ee332 100644
> --- a/drivers/platform/x86/lenovo/ideapad-laptop.c
> +++ b/drivers/platform/x86/lenovo/ideapad-laptop.c
> @@ -178,6 +178,7 @@ struct ideapad_private {
>  	struct ideapad_rfk_priv rfk_priv[IDEAPAD_RFKILL_DEV_NUM];
>  	struct platform_device *platform_device;
>  	struct input_dev *inputdev;
> +	struct input_dev *camera_switch_idev;
>  	struct backlight_device *blightdev;
>  	struct ideapad_dytc_priv *dytc;
>  	struct dentry *debug;
> @@ -1410,10 +1411,43 @@ static int ideapad_input_init(struct ideapad_private *priv)
>  	return err;
>  }
>  
> +static int ideapad_camera_switch_init(struct ideapad_private *priv, bool covered)
> +{
> +	struct input_dev *idev;
> +	int err;
> +
> +	idev = input_allocate_device();
> +	if (!idev)
> +		return -ENOMEM;
> +
> +	idev->name = "Ideapad Camera Switch";
> +	idev->phys = "ideapad/input1";
> +	idev->id.bustype = BUS_HOST;
> +	idev->dev.parent = &priv->platform_device->dev;
> +
> +	input_set_capability(idev, EV_SW, SW_CAMERA_LENS_COVER);
> +	input_report_switch(idev, SW_CAMERA_LENS_COVER, covered);
> +	input_sync(idev);
> +
> +	err = input_register_device(idev);
> +	if (err) {
> +		input_free_device(idev);
> +		return err;
> +	}
> +
> +	priv->camera_switch_idev = idev;
> +	return 0;
> +}
> +
>  static void ideapad_input_exit(struct ideapad_private *priv)
>  {
>  	input_unregister_device(priv->inputdev);
>  	priv->inputdev = NULL;
> +
> +	if (priv->camera_switch_idev) {
> +		input_unregister_device(priv->camera_switch_idev);
> +		priv->camera_switch_idev = NULL;
> +	}
>  }
>  
>  static void ideapad_input_report(struct ideapad_private *priv,
> @@ -1422,6 +1456,22 @@ static void ideapad_input_report(struct ideapad_private *priv,
>  	sparse_keymap_report_event(priv->inputdev, scancode, 1, true);
>  }
>  
> +static void ideapad_camera_switch_report(struct ideapad_private *priv, bool covered)
> +{
> +	/* The WMI notify path is serialized through ideapad_shared_mutex */
> +	lockdep_assert_held(&ideapad_shared_mutex);
> +
> +	if (!priv->camera_switch_idev) {
> +		if (ideapad_camera_switch_init(priv, covered))
> +			dev_warn_once(&priv->platform_device->dev,
> +				      "Failed to register camera switch input device\n");
> +		return;
> +	}
> +
> +	input_report_switch(priv->camera_switch_idev, SW_CAMERA_LENS_COVER, covered);
> +	input_sync(priv->camera_switch_idev);
> +}
> +
>  static void ideapad_input_novokey(struct ideapad_private *priv)
>  {
>  	unsigned long long_pressed;
> @@ -2312,6 +2362,15 @@ static void ideapad_wmi_notify(struct wmi_device *wdev, union acpi_object *data)
>  			break;
>  		}
>  
> +		/*
> +		 * Camera switch, handled by the firmware:
> +		 * 0x0c camera enabled, 0x0d camera disabled
> +		 */
> +		if (data->integer.value == 0x0c || data->integer.value == 0x0d) {
> +			ideapad_camera_switch_report(priv, data->integer.value == 0x0d);
> +			break;
> +		}
> +
>  		/* 0x02 FnLock, 0x03 Esc */
>  		if (data->integer.value == 0x02 || data->integer.value == 0x03)
>  			ideapad_fn_lock_led_notify(priv, data->integer.value == 0x02);
> 
> base-commit: f475845eaf3d749114a63270bf2efea459e14dd2
From 69aff9a8705e2ee28a59722fa133c6e492fe526a Mon Sep 17 00:00:00 2001
From: Rong Zhang <i@xxxxxxxx>
Date: Mon, 21 Sep 2026 21:47:17 +0800
Subject: [PATCH v3] platform/x86: ideapad-laptop: Report camera switch as SW_CAMERA_LENS_COVER
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 7bit
Message-Id: <20260921-ideapad-laptop-camera-sw-v3-1-f028f007f6d7@xxxxxxxx>
X-Change-ID: 8511c6da-ideapad-laptop-camera-sw-948e4653b20e

On certain 2025 Lenovo laptops, such as the Yoga Pro 7 14ASP10 and Legion
Pro 7 16AFR10H, a switch on the side disables the camera. This is handled
by the firmware, which also sends event 0x0d (camera disabled) or 0x0c
(camera enabled) through the WMI event GUID handled with
ideapad_wmi_context_fn_keys. These events are currently reported as
KEY_UNKNOWN.

Other Lenovo laptops expose a similar camera switch through a separate WMI
GUID, which lenovo-wmi-camera reports as SW_CAMERA_LENS_COVER since
commit d98bf6a6ed61 ("platform/x86: lenovo-wmi-camera: Use
SW_CAMERA_LENS_COVER instead of KEY_CAMERA_ACESS"). That driver does not
bind on these laptops, so map the WMI events to SW_CAMERA_LENS_COVER as
well via sparse keymap KE_SW.

Co-developed-by: Marco Giunta <marco_giunta@xxxxxxxxxx>
Signed-off-by: Marco Giunta <marco_giunta@xxxxxxxxxx>
Signed-off-by: Rong Zhang <i@xxxxxxxx>
---
 drivers/platform/x86/lenovo/ideapad-laptop.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/platform/x86/lenovo/ideapad-laptop.c b/drivers/platform/x86/lenovo/ideapad-laptop.c
index 8213524504ee..3e91cc1df6c2 100644
--- a/drivers/platform/x86/lenovo/ideapad-laptop.c
+++ b/drivers/platform/x86/lenovo/ideapad-laptop.c
@@ -1365,6 +1365,18 @@ static const struct key_entry ideapad_keymap[] = {
 	{ KE_KEY,   0x29 | IDEAPAD_WMI_KEY, { KEY_TOUCHPAD_TOGGLE } },
 	{ KE_KEY,   0x2a | IDEAPAD_WMI_KEY, { KEY_ROOT_MENU } },
 
+	/*
+	 * WMI switches
+	 *
+	 * Some devices come with physical switches. Whenever a switch is
+	 * toggled, an WMI event is emitted to inform the software about the
+	 * switch's latest state.
+	 */
+
+	/* Camera switch */
+	{ KE_SW,	0x0c | IDEAPAD_WMI_KEY, .sw = { SW_CAMERA_LENS_COVER, 0 } },
+	{ KE_SW,	0x0d | IDEAPAD_WMI_KEY, .sw = { SW_CAMERA_LENS_COVER, 1 } },
+
 	{ KE_END },
 };
 

---
base-commit: 518e5b794c06c0f0eb40df3e202274a66202c137
change-id: 8511c6da-ideapad-laptop-camera-sw-948e4653b20e

Thanks,
Rong