Re: [PATCH] platform/x86: dell-privacy: Add support for new privacy driver

["Barnabás Pőcze" <pobrn@protonmail.com>]

Hi

(I really hope Hans and Mark won't get mad at me for writing some thoughts about
this patch.)

First of all, indentation should be tabs (= 8 spaces), not spaces. If I see it
correctly, the two are mixed here.

And please make the printed messages consistent (capitalization, etc.),
I believe punctuation at the end is not necessary, and don't leave whitespaces
between the text and newline character. Please always run `checkpatch` on the patch
to see what can/needs to be improved.

There are also parts in the code (variables not actually used, etc.) that make me
feel like it's somewhat unfinished, or rather, incomplete.

Both `dell-privacy-acpi` and `dell-privacy-wmi` have the same comment:
"Dell privacy notification driver", but surely they are not the same thing?

I have also added a couple comments inline.


> From: perry_yuan <perry_yuan@dell.com>
>
>  add support for dell privacy driver for the dell units equipped
>  hardware privacy design, which protect users privacy
>  of audio and camera from hardware level. once the audio or camera
>  privacy mode enabled, any applications will not get any audio or
>  video stream.
>  when user pressed ctrl+F4 hotkey, audio privacy mode will be enabled
>  and camera mute hotkey is ctrl+F9.
>
> Signed-off-by: Perry Yuan  <perry_yuan@dell.com>
> Signed-off-by: Limonciello Mario <mario_limonciello@dell.com>
> ---
>  drivers/platform/x86/Kconfig             |  12 ++
>  drivers/platform/x86/Makefile            |   4 +-
>  drivers/platform/x86/dell-laptop.c       |  41 ++--
>  drivers/platform/x86/dell-privacy-acpi.c | 139 ++++++++++++
>  drivers/platform/x86/dell-privacy-wmi.c  | 259 +++++++++++++++++++++++
>  drivers/platform/x86/dell-privacy-wmi.h  |  23 ++
>  drivers/platform/x86/dell-wmi.c          |  90 ++++----
>  7 files changed, 513 insertions(+), 55 deletions(-)
>  create mode 100644 drivers/platform/x86/dell-privacy-acpi.c
>  create mode 100644 drivers/platform/x86/dell-privacy-wmi.c
>  create mode 100644 drivers/platform/x86/dell-privacy-wmi.h
>
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index 40219bba6801..0cb6bf5a9565 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -454,6 +454,18 @@ config DELL_WMI_LED
>  	  This adds support for the Latitude 2100 and similar
>  	  notebooks that have an external LED.
>
> +config DELL_PRIVACY
> +        tristate "Dell Hardware Privacy Support"
> +        depends on ACPI
> +        depends on ACPI_WMI
> +        depends on INPUT
> +        depends on DELL_LAPTOP
> +        select DELL_WMI
> +        help
> +          This driver provides a driver to support messaging related to the

I'm not a native English speaker, but "messaging" seems a strange choice of
words to me here.


> +          privacy button presses on applicable Dell laptops from 2021 and
> +          newer.

I have the same feeling about "from 2021 and newer".


> +
>  config AMILO_RFKILL
>  	tristate "Fujitsu-Siemens Amilo rfkill support"
>  	depends on RFKILL
> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> index 5f823f7eff45..111f7215db2f 100644
> --- a/drivers/platform/x86/Makefile
> +++ b/drivers/platform/x86/Makefile
> @@ -47,7 +47,9 @@ obj-$(CONFIG_DELL_WMI)			+= dell-wmi.o
>  obj-$(CONFIG_DELL_WMI_DESCRIPTOR)	+= dell-wmi-descriptor.o
>  obj-$(CONFIG_DELL_WMI_AIO)		+= dell-wmi-aio.o
>  obj-$(CONFIG_DELL_WMI_LED)		+= dell-wmi-led.o
> -
> +obj-$(CONFIG_DELL_PRIVACY)              += dell-privacy.o
> +dell-privacy-objs                       := dell-privacy-wmi.o \
> +	                                   dell-privacy-acpi.o
>  # Fujitsu
>  obj-$(CONFIG_AMILO_RFKILL)	+= amilo-rfkill.o
>  obj-$(CONFIG_FUJITSU_LAPTOP)	+= fujitsu-laptop.o
> diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
> index 5e9c2296931c..12b91de09356 100644
> -- a/drivers/platform/x86/dell-laptop.c
> ++ b/drivers/platform/x86/dell-laptop.c
> @@ -30,6 +30,7 @@
> #include <acpi/video.h>
> #include "dell-rbtn.h"
> #include "dell-smbios.h"
> #include "dell-privacy-wmi.h"
>
> struct quirk_entry {
> 	bool touchpad_led;
> @@ -90,6 +91,7 @@ static struct rfkill *wifi_rfkill;
> static struct rfkill *bluetooth_rfkill;
> static struct rfkill *wwan_rfkill;
> static bool force_rfkill;
> static bool privacy_valid;
>
> module_param(force_rfkill, bool, 0444);
> MODULE_PARM_DESC(force_rfkill, "enable rfkill on non whitelisted models");
> @@ -2202,20 +2204,25 @@ static int __init dell_init(void)
> 	debugfs_create_file("rfkill", 0444, dell_laptop_dir, NULL,
> 			    &dell_debugfs_fops);
>
> 	dell_laptop_register_notifier(&dell_laptop_notifier);
>
> 	if (dell_smbios_find_token(GLOBAL_MIC_MUTE_DISABLE) &&
> 	    dell_smbios_find_token(GLOBAL_MIC_MUTE_ENABLE)) {
> 		micmute_led_cdev.brightness = ledtrig_audio_get(LED_AUDIO_MICMUTE);
> 		ret = led_classdev_register(&platform_device->dev, &micmute_led_cdev);
> 		if (ret < 0)
> 			goto fail_led;
> 	}
>
> 	if (acpi_video_get_backlight_type() != acpi_backlight_vendor)
> 		return 0;
>
> 	token = dell_smbios_find_token(BRIGHTNESS_TOKEN);
>     dell_laptop_register_notifier(&dell_laptop_notifier);
>
>     if (dell_smbios_find_token(GLOBAL_MIC_MUTE_DISABLE) &&
>             dell_smbios_find_token(GLOBAL_MIC_MUTE_ENABLE)) {
> #if IS_ENABLED(CONFIG_DELL_PRIVACY)
>         privacy_valid = dell_privacy_valid() == -ENODEV;

`dell_privacy_valid()` returns `bool`.


> #endif
>         if (!privacy_valid) {
>             micmute_led_cdev.brightness = ledtrig_audio_get(LED_AUDIO_MICMUTE);
>             ret = led_classdev_register(&platform_device->dev, &micmute_led_cdev);
>             if (ret < 0)
>                 goto fail_led;
>         }
>     }
>
>     if (acpi_video_get_backlight_type() != acpi_backlight_vendor)
>         return 0;
>
>     token = dell_smbios_find_token(BRIGHTNESS_TOKEN);
> 	if (token) {
> 		struct calling_interface_buffer buffer;
>
> @@ -2257,7 +2264,8 @@ static int __init dell_init(void)
> fail_get_brightness:
> 	backlight_device_unregister(dell_backlight_device);
> fail_backlight:
> 	led_classdev_unregister(&micmute_led_cdev);
>     if (!privacy_valid)
>         led_classdev_unregister(&micmute_led_cdev);
> fail_led:
> 	dell_cleanup_rfkill();
> fail_rfkill:
> @@ -2278,7 +2286,8 @@ static void __exit dell_exit(void)
> 		touchpad_led_exit();
> 	kbd_led_exit();
> 	backlight_device_unregister(dell_backlight_device);
> 	led_classdev_unregister(&micmute_led_cdev);
>     if (!privacy_valid)
>         led_classdev_unregister(&micmute_led_cdev);
> 	dell_cleanup_rfkill();
> 	if (platform_device) {
> 		platform_device_unregister(platform_device);
> diff --git a/drivers/platform/x86/dell-privacy-acpi.c b/drivers/platform/x86/dell-privacy-acpi.c
> new file mode 100644
> index 000000000000..516cd99167c3
> --- /dev/null
> +++ b/drivers/platform/x86/dell-privacy-acpi.c
> @@ -0,0 +1,139 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Dell privacy notification driver
> + *
> + * Copyright (C) 2021 Dell Inc. All Rights Reserved.
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/acpi.h>
> +#include <linux/device.h>
> +#include <linux/fs.h>
> +#include <linux/kernel.h>
> +#include <linux/leds.h>
> +#include <linux/module.h>
> +#include <linux/string.h>
> +#include <linux/sysfs.h>
> +#include <linux/types.h>
> +#include <linux/wmi.h>
> +#include <linux/slab.h>
> +#include <linux/platform_device.h>
> +#include "dell-privacy-wmi.h"
> +
> +#define PRIVACY_PlATFORM_NAME  "dell-privacy-acpi"
                    ^
should be upper case


> +#define ACPI_PRIVACY_DEVICE	"\\_SB.PC00.LPCB.ECDV"
> +#define ACPI_PRIVACY_EC_ACK	ACPI_PRIVACY_DEVICE ".ECAK"
> +
> +static struct platform_device *privacy_acpi_pdev;
> +
> +struct privacy_acpi_priv {
> +    struct device *dev;
> +    struct acpi_device *acpi_dev;
> +    struct input_dev *input_dev;
> +    struct platform_device *platform_device;
> +};
> +
> +static int micmute_led_set(struct led_classdev *led_cdev,
> +               enum led_brightness brightness)
> +{
> +    acpi_status status;
> +
> +    status = acpi_evaluate_object(NULL, ACPI_PRIVACY_EC_ACK, NULL, NULL);

The handle of "ACPI_PRIVACY_DEVICE" is queried in `privacy_acpi_probe()`. Why
is that not used here?


> +    if (ACPI_FAILURE(status)) {
> +        dev_err(led_cdev->dev, "Error setting privacy audio EC ack value: %d\n",status);
                                                                                   ^
                                                                   missing space -/

I think `acpi_format_exception()` could be used here.

I don't quite see why brightness is completely ignored? Does this just toggle
the LED state? Even in that case I think something should be done to avoid the
sysfs attribute showing brightness=1 while the LED is actually off.

Does the `ACPI_PRIVACY_EC_ACK` method (?) acknowledge something? If so, what? And
why is it called in the brightness setting method of a LED class device?


> +        return -EIO;
> +    }
> +    return 0;
> +}
> +
> +static struct led_classdev micmute_led_cdev = {
> +    .name = "platform::micmute",
> +    .max_brightness = 1,
> +    .brightness_set_blocking = micmute_led_set,
> +    .default_trigger = "audio-micmute",
> +};

There is also the exact same `micmute_led_cdev` is in dell-laptop.c. Both are
valid? What's the difference? Why can't the LED be handled in just a single place?


> [...]
> +static const struct acpi_device_id privacy_acpi_device_ids[] = {
> +    {"PNP0C09", 0},
> +    {"", 0},
> +};
> +MODULE_DEVICE_TABLE(acpi, privacy_acpi_device_ids);
> +
> +static struct platform_driver privacy_platform_driver = {
> +    .driver     = {
> +        .name   = PRIVACY_PlATFORM_NAME,
> +        .acpi_match_table = ACPI_PTR(privacy_acpi_device_ids),
> +    },
> +    .probe      = privacy_acpi_probe,
> +    .remove     = privacy_acpi_remove,
> +};
> +
> +int privacy_acpi_init(void)
> +{
> +    int err;
> +
> +    err = platform_driver_register(&privacy_platform_driver);
> +    if (err)
> +        return err;
> +
> +    privacy_acpi_pdev = platform_device_register_simple(
> +            PRIVACY_PlATFORM_NAME, -1, NULL, 0);
> +    if (IS_ERR(privacy_acpi_pdev)) {
> +        err = PTR_ERR(privacy_acpi_pdev);
> +        goto err_platform;
> +    }
> +    return 0;
> +
> +err_platform:
> +    platform_driver_unregister(&privacy_platform_driver);
> +    return err;
> +}

Maybe I'm missing something obvious, but I do believe this is overly complicated.
I don't see why you cannot check the ACPI path, if it exists, register
a platform device, and then register the led to that device? The whole platform driver
part could've been avoided as far as I see.

I'm also wondering if the ACPI path is enough to decide undoubtedly that this
is indeed a compatible device.


> +
> +void privacy_acpi_cleanup(void)
> +{
> +    platform_driver_unregister(&privacy_platform_driver);
> +}

The platform device is not cleaned up.


> +
> +MODULE_AUTHOR("Perry Yuan <perry_yuan@dell.com>");
> +MODULE_DESCRIPTION("DELL Privacy ACPI Driver");
> +MODULE_LICENSE("GPL");
> +
> diff --git a/drivers/platform/x86/dell-privacy-wmi.c b/drivers/platform/x86/dell-privacy-wmi.c
> new file mode 100644
> index 000000000000..6c36b7ec44c6
> --- /dev/null
> +++ b/drivers/platform/x86/dell-privacy-wmi.c
> @@ -0,0 +1,259 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Dell privacy notification driver
> + *
> + * Copyright (C) 2021 Dell Inc. All Rights Reserved.
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/acpi.h>
> +#include <linux/input.h>
> +#include <linux/input/sparse-keymap.h>
> +#include <linux/list.h>
> +#include <linux/module.h>
> +#include <linux/wmi.h>
> +#include "dell-privacy-wmi.h"
> +
> +#define DELL_PRIVACY_GUID "6932965F-1671-4CEB-B988-D3AB0A901919"
> +#define MICROPHONE_STATUS		    BIT(0)
> +#define CAMERA_STATUS		        BIT(1)
> +#define PRIVACY_SCREEN_STATUS		BIT(2)

`#include <linux/bits.h>`?


> +
> +static int privacy_valid = -EPROBE_DEFER;
> +static LIST_HEAD(wmi_list);
> +static DEFINE_MUTEX(list_mutex);

What is the purpose of this list? At the moment I can't really see it.


> +
> +struct privacy_wmi_data {
> +    struct input_dev *input_dev;
> +    struct wmi_device *wdev;
> +    struct list_head list;
> +    u32 features_present;
> +    u32 last_status;

`last_status` and `features_present` are there for no actual benefit.


> +};
> +
> +/*
> + * Keymap for WMI Privacy events of type 0x0012
> + */
> +static const struct key_entry dell_wmi_keymap_type_0012[] = {
> +    /* Privacy MIC Mute */
> +    { KE_KEY, 0x0001, { KEY_MICMUTE } },
> +    /* Privacy Camera Mute */
> +    { KE_SW,  0x0002, { SW_CAMERA_LENS_COVER } },

I see the calloc trick later to avoid writing KE_END, but I still think it'd be
better if there was an explicit KE_END entry.


> +};
> +
> +bool dell_privacy_valid(void)
> +{
> +    bool ret;
> +
> +    mutex_lock(&list_mutex);
> +    ret = wmi_has_guid(DELL_PRIVACY_GUID);
> +    if (!ret){
> +        return -ENODEV;

The functions returns `bool`.


> +    }
> +    ret = privacy_valid;

I'm not sure if it's a good idea to just plainly assign an `int` to a `bool`.


> +    mutex_unlock(&list_mutex);
> +
> +    return ret;
> +}
> +EXPORT_SYMBOL_GPL(dell_privacy_valid);

Instead of always querying for the presence of the WMI GUID, wouldn't a single
atomic_t or similar be sufficient?


> +
> +void dell_privacy_process_event(int type, int code, int status)
> +{
> +    struct privacy_wmi_data *priv;
> +    const struct key_entry *key;
> +
> +    mutex_lock(&list_mutex);
> +    priv = list_first_entry_or_null(&wmi_list,
> +            struct privacy_wmi_data,
> +            list);
> +    if (priv == NULL) {

`if (!priv)`


> +        pr_err("dell privacy priv is NULL\n");
> +        goto error;
> +    }
> +
> +    key = sparse_keymap_entry_from_scancode(priv->input_dev, (type << 16)|code);
> +    if (!key) {
> +        dev_dbg(&priv->wdev->dev, "Unknown key with type 0x%04x and code 0x%04x pressed\n",
> +                type, code);
> +        goto error;
> +    }
> +
> +    switch (code) {
> +        case DELL_PRIVACY_TYPE_AUDIO: /* Mic mute */
> +            priv->last_status = status;
> +            sparse_keymap_report_entry(priv->input_dev, key, 1, true);
> +            break;
> +        case DELL_PRIVACY_TYPE_CAMERA: /* Camera mute */
> +            priv->last_status = status;
> +            sparse_keymap_report_entry(priv->input_dev, key, 1, true);
> +            break;
> +        default:
> +            dev_dbg(&priv->wdev->dev, "unknown event type %u /%u",

A couple lines above hexadecimal format and capitalization is used.


> +                    type, code);
> +    }
> +error:
> +    mutex_unlock(&list_mutex);
> +    return;
> +}
> +EXPORT_SYMBOL_GPL(dell_privacy_process_event);
> [...]
> +static int dell_privacy_wmi_probe(struct wmi_device *wdev, const void *context)
> +{
> +    struct privacy_wmi_data *priv;
> +    struct key_entry *keymap;
> +    int ret, i, pos = 0;
> +
> +    priv = devm_kzalloc(&wdev->dev, sizeof(struct privacy_wmi_data),
> +            GFP_KERNEL);

`sizeof(*priv)`


> +    if (!priv)
> +        return -ENOMEM;
> +
> +    /* create evdev passing interface */
> +    priv->input_dev = devm_input_allocate_device(&wdev->dev);
> +    if (!priv->input_dev)
> +        return -ENOMEM;
> +
> +    __set_bit(EV_KEY, priv->input_dev->evbit);
> +    __set_bit(KEY_MICMUTE, priv->input_dev->keybit);
> +    __set_bit(EV_MSC, priv->input_dev->evbit);
> +    __set_bit(MSC_SCAN, priv->input_dev->mscbit);

`sparse_keymap_setup()` takes care of this.


> +    keymap = kcalloc(
> +            ARRAY_SIZE(dell_wmi_keymap_type_0012) +
> +            1,
> +            sizeof(struct key_entry), GFP_KERNEL);
> +    if (!keymap) {
> +        ret = -ENOMEM;
> +        goto err_free_dev;
> +    }
> +    for (i = 0; i < ARRAY_SIZE(dell_wmi_keymap_type_0012); i++) {
> +        keymap[pos] = dell_wmi_keymap_type_0012[i];
> +        keymap[pos].code |= (0x0012 << 16);
> +        pos++;
> +    }

I can't quite see why you need a copy of the entries. If the key codes are initialized
to the "correct" values, this can be avoided altogether.


> +    ret = sparse_keymap_setup(priv->input_dev, keymap, NULL);
> +    if (ret)
> +        return ret;
> +
> +    priv->input_dev->dev.parent = &wdev->dev;
> +    priv->input_dev->name = "Dell Privacy Driver";
> +    priv->input_dev->id.bustype = BUS_HOST;
> +
> +    if (input_register_device(priv->input_dev)) {
> +        pr_debug("input_register_device failed to register! \n");
> +        return -ENODEV;

`keymap` is leaked here.


> +    }
> +
> +    priv->wdev = wdev;
> +    dev_set_drvdata(&wdev->dev, priv);
> +    mutex_lock(&list_mutex);
> +    list_add_tail(&priv->list, &wmi_list);
> +    privacy_valid = true;
> +    if (get_current_status(wdev)) {
> +        goto err_free_dev;

Mutex is not unlocked. And some steps are not undone.


> +    }
> +    mutex_unlock(&list_mutex);
> +    kfree(keymap);
> +    return 0;
> +
> +err_free_dev:
> +    input_free_device(priv->input_dev);
> +    kfree(keymap);
> +    return ret;
> +}
> +
> +static int dell_privacy_wmi_remove(struct wmi_device *wdev)
> +{
> +    struct privacy_wmi_data *priv = dev_get_drvdata(&wdev->dev);
> +
> +    mutex_lock(&list_mutex);
> +    list_del(&priv->list);
> +    privacy_valid = -ENODEV;
> +    mutex_unlock(&list_mutex);
> +    return 0;
> +}
> +
> +static const struct wmi_device_id dell_wmi_privacy_wmi_id_table[] = {
> +    { .guid_string = DELL_PRIVACY_GUID },
> +    { },
> +};
> +
> +static struct wmi_driver dell_privacy_wmi_driver = {
> +    .driver = {
> +        .name = "dell-privacy",
> +    },
> +    .probe = dell_privacy_wmi_probe,
> +    .remove = dell_privacy_wmi_remove,
> +    .id_table = dell_wmi_privacy_wmi_id_table,
> +};
> +
> +static int __init init_dell_privacy(void)
> +{
> +    int ret, wmi, acpi;

`int ret;` would've been enough. The preferred and prevalent style is:

```
int ret;

ret = step_1();
if (ret) {
  pr_err(...);
  goto undo_step_1;
}

ret = step_2();
if (ret) {
  pr_err(...);
  goto undo_step_2;
}

...

return 0;


undo_step_2:
  ...
undo_step_1:
  ....

return ret;
```


> +
> +    wmi = wmi_driver_register(&dell_privacy_wmi_driver);
> +    if (wmi) {
> +        pr_debug("Failed to initialize privacy wmi driver: %d\n", wmi);
> +        return wmi;
> +    }
> +
> +    acpi = privacy_acpi_init();
> +    if (acpi) {
> +        pr_debug("failed to initialize privacy wmi acpi driver: %d\n", acpi);
> +        return acpi;
> +    }
> +
> +    return 0;
> +}

Even ignoring stylistic questions, the WMI driver is not unregistered if
`privacy_acpi_init()` fails, which is a bigger problem.

Even ignoring that, I'm not sure it's a good idea that a module that exports
symbols for others to use can fail to load.


> +
> +void exit_dell_privacy_wmi(void)
> +{
> +    wmi_driver_unregister(&dell_privacy_wmi_driver);
> +}

At the moment I can't quite see the purpose of this function.


> +
> +static void __exit exit_dell_privacy(void)
> +{
> +    privacy_acpi_cleanup();
> +    exit_dell_privacy_wmi();
> +}
> +
> +module_init(init_dell_privacy);
> +module_exit(exit_dell_privacy);
> +
> +MODULE_DEVICE_TABLE(wmi, dell_wmi_privacy_wmi_id_table);

A couple lines above the `MODULE_DEVICE_TABLE` macro was invoked right after
the device table.


> +MODULE_AUTHOR("Perry Yuan <perry_yuan@dell.com>");
> +MODULE_DESCRIPTION("Dell Privacy WMI Driver");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/platform/x86/dell-privacy-wmi.h b/drivers/platform/x86/dell-privacy-wmi.h
> new file mode 100644
> index 000000000000..94af81d76e44
> --- /dev/null
> +++ b/drivers/platform/x86/dell-privacy-wmi.h
> @@ -0,0 +1,23 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Dell privacy notification driver
> + *
> + * Copyright (C) 2021 Dell Inc. All Rights Reserved.
> + */
> +
> +#ifndef _DELL_PRIVACY_WMI_H_
> +#define _DELL_PRIVACY_WMI_H_
> +#include <linux/wmi.h>

This include is not needed.


> +
> +bool dell_privacy_valid(void);
> +void dell_privacy_process_event(int type, int code, int status);
> +int  privacy_acpi_init(void);
> +void privacy_acpi_cleanup(void);

These aren't prefixed by `dell_`?


> +
> +/* DELL Privacy Type */
> +enum {
> +	DELL_PRIVACY_TYPE_UNKNOWN = 0x0,
> +	DELL_PRIVACY_TYPE_AUDIO,
> +	DELL_PRIVACY_TYPE_CAMERA,
> +};
> +#endif
> diff --git a/drivers/platform/x86/dell-wmi.c b/drivers/platform/x86/dell-wmi.c
> index bbdb3e860892..44bb74e4df86 100644
> --- a/drivers/platform/x86/dell-wmi.c
> +++ b/drivers/platform/x86/dell-wmi.c
> @@ -27,6 +27,7 @@
>  #include <acpi/video.h>
>  #include "dell-smbios.h"
>  #include "dell-wmi-descriptor.h"
> +#include "dell-privacy-wmi.h"
>
>  MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
>  MODULE_AUTHOR("Pali Rohár <pali@kernel.org>");
> @@ -410,44 +411,57 @@ static void dell_wmi_notify(struct wmi_device *wdev,
>  		if (buffer_end > buffer_entry + buffer_entry[0] + 1)
>  			buffer_end = buffer_entry + buffer_entry[0] + 1;
>
> -	while (buffer_entry < buffer_end) {
> -
> -		len = buffer_entry[0];
> -		if (len == 0)
> -			break;
> -
> -		len++;
> -
> -		if (buffer_entry + len > buffer_end) {
> -			pr_warn("Invalid length of WMI event\n");
> -			break;
> -		}
> -
> -		pr_debug("Process buffer (%*ph)\n", len*2, buffer_entry);
> -
> -		switch (buffer_entry[1]) {
> -		case 0x0000: /* One key pressed or event occurred */
> -		case 0x0012: /* Event with extended data occurred */
> -			if (len > 2)
> -				dell_wmi_process_key(wdev, buffer_entry[1],
> -						     buffer_entry[2]);
> -			/* 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]);
> -			break;
> -		default: /* Unknown event */
> -			pr_info("Unknown WMI event type 0x%x\n",
> -				(int)buffer_entry[1]);
> -			break;
> -		}
> -
> -		buffer_entry += len;
> -
> -	}
> +    while (buffer_entry < buffer_end) {
> +
> +        len = buffer_entry[0];
> +        if (len == 0)
> +            break;
> +
> +        len++;
> +
> +        if (buffer_entry + len > buffer_end) {
> +            pr_warn("Invalid length of WMI event\n");
> +            break;
> +        }
> +
> +        pr_debug("Process buffer (%*ph)\n", len*2, buffer_entry);
> +
> +        switch (buffer_entry[1]) {
> +            case 0x0000: /* One key pressed or event occurred */
> +                if (len > 2)
> +                    dell_wmi_process_key(wdev, buffer_entry[1],
> +                            buffer_entry[2]);
> +                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]);
> +                break;
> +            case 0x0012:
> +#if IS_ENABLED(CONFIG_DELL_PRIVACY)
> +                if (dell_privacy_valid()) {
> +                    dell_privacy_process_event(buffer_entry[1], buffer_entry[3],
> +                            buffer_entry[4]);
> +                } else {
> +                    if (len > 2)
> +                        dell_wmi_process_key(wdev, buffer_entry[1], buffer_entry[2]);
> +                }
> +#else
> +                /* Extended data is currently ignored */
> +                if (len > 2)
> +                    dell_wmi_process_key(wdev, buffer_entry[1], buffer_entry[2]);
> +#endif

Wouldn't it be better if the header file provided a static inline definitions
for `dell_privacy_valid()` and `dell_privacy_process_event()` - if CONFIG_DELL_PRIVACY
is not enabled - that return false and do nothing, respectively? The same way
it's done in dell-smbios.h.


> +                break;
> +            default: /* Unknown event */
> +                pr_info("Unknown WMI event type 0x%x\n",
> +                        (int)buffer_entry[1]);
> +                break;
> +        }
> +
> +        buffer_entry += len;
> +
> +    }
>
>  }
> [...]


Regards,
Barnabás Pőcze