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From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>
Date: Fri, 15 Mar 2024 19:54:22 +0200 (EET)
To: Armin Wolf <W_Armin@gmx.de>
cc: Ai Chao <aichao@kylinos.cn>, Hans de Goede <hdegoede@redhat.com>, 
    LKML <linux-kernel@vger.kernel.org>, platform-driver-x86@vger.kernel.org
Subject: Re: [PATCH v8] platform/x86: add lenovo wmi camera button driver
In-Reply-To: <a2db8f76-d0c3-402e-9fb0-13f36c848607@gmx.de>
Message-ID: <c3dba443-89d5-96cb-3e40-a4e3ab87002e@linux.intel.com>
References: <20240314050319.171816-1-aichao@kylinos.cn> <d7c2de21-50f9-4602-abd0-b83ecbc3f42f@gmx.de> <62b54638-92eb-52e1-d4ad-074963771157@linux.intel.com> <a2db8f76-d0c3-402e-9fb0-13f36c848607@gmx.de>
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On Fri, 15 Mar 2024, Armin Wolf wrote:
> Am 15.03.24 um 12:51 schrieb Ilpo J=C3=A4rvinen:
> > On Thu, 14 Mar 2024, Armin Wolf wrote:
> > > Am 14.03.24 um 06:03 schrieb Ai Chao:
> > >=20
> > > > Add lenovo generic wmi driver to support camera button.
> > > > The Camera button is a GPIO device. This driver receives ACPI notif=
yi
> > > > when the camera button is switched on/off. This driver is used in
> > > > Lenovo A70, it is a Computer integrated machine.
> > > >=20
> > > > Signed-off-by: Ai Chao <aichao@kylinos.cn>
> > > > ---
> > > > v8: Dev_deb convert to dev_err.
> > > > v7: Add dev_dbg and remove unused dev in struct.
> > > > v6: Modify SW_CAMERA_LENS_COVER to
> > > > KEY_CAMERA_ACCESS_ENABLE/KEY_CAMERA_ACCESS_DISABLE.
> > > > v5: Remove camera button groups, modify KEY_CAMERA to
> > > > SW_CAMERA_LENS_COVER.
> > > > v4: Remove lenovo_wmi_input_setup, move camera_mode into struct
> > > > lenovo_wmi_priv.
> > > > v3: Remove lenovo_wmi_remove function.
> > > > v2: Adjust GPL v2 to GPL, adjust sprintf to sysfs_emit.
> > > >=20
> > > >    drivers/platform/x86/Kconfig             |  12 +++
> > > >    drivers/platform/x86/Makefile            |   1 +
> > > >    drivers/platform/x86/lenovo-wmi-camera.c | 108
> > > > +++++++++++++++++++++++
> > > >    3 files changed, 121 insertions(+)
> > > >    create mode 100644 drivers/platform/x86/lenovo-wmi-camera.c
> > > >=20
> > > > diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kc=
onfig
> > > > index bdd302274b9a..9506a455b547 100644
> > > > --- a/drivers/platform/x86/Kconfig
> > > > +++ b/drivers/platform/x86/Kconfig
> > > > @@ -1001,6 +1001,18 @@ config INSPUR_PLATFORM_PROFILE
> > > >    =09To compile this driver as a module, choose M here: the module
> > > >    =09will be called inspur-platform-profile.
> > > >=20
> > > > +config LENOVO_WMI_CAMERA
> > > > +=09tristate "Lenovo WMI Camera Button driver"
> > > > +=09depends on ACPI_WMI
> > > > +=09depends on INPUT
> > > > +=09help
> > > > +=09  This driver provides support for Lenovo camera button. The Ca=
mera
> > > > +=09  button is a GPIO device. This driver receives ACPI notify whe=
n the
> > > > +=09  camera button is switched on/off.
> > > > +
> > > > +=09  To compile this driver as a module, choose M here: the module
> > > > +=09  will be called lenovo-wmi-camera.
> > > > +
> > > >    source "drivers/platform/x86/x86-android-tablets/Kconfig"
> > > >=20
> > > >    config FW_ATTR_CLASS
> > > > diff --git a/drivers/platform/x86/Makefile
> > > > b/drivers/platform/x86/Makefile
> > > > index 1de432e8861e..217e94d7c877 100644
> > > > --- a/drivers/platform/x86/Makefile
> > > > +++ b/drivers/platform/x86/Makefile
> > > > @@ -66,6 +66,7 @@ obj-$(CONFIG_SENSORS_HDAPS)=09+=3D hdaps.o
> > > >    obj-$(CONFIG_THINKPAD_ACPI)=09+=3D thinkpad_acpi.o
> > > >    obj-$(CONFIG_THINKPAD_LMI)=09+=3D think-lmi.o
> > > >    obj-$(CONFIG_YOGABOOK)=09=09+=3D lenovo-yogabook.o
> > > > +obj-$(CONFIG_LENOVO_WMI_CAMERA)=09+=3D lenovo-wmi-camera.o
> > > >=20
> > > >    # Intel
> > > >    obj-y=09=09=09=09+=3D intel/
> > > > diff --git a/drivers/platform/x86/lenovo-wmi-camera.c
> > > > b/drivers/platform/x86/lenovo-wmi-camera.c
> > > > new file mode 100644
> > > > index 000000000000..f83e3ccd9189
> > > > --- /dev/null
> > > > +++ b/drivers/platform/x86/lenovo-wmi-camera.c
> > > > @@ -0,0 +1,108 @@
> > > > +// SPDX-License-Identifier: GPL-2.0
> > > > +/*
> > > > + * Lenovo WMI Camera Button Driver
> > > > + *
> > > > + * Author: Ai Chao <aichao@kylinos.cn>
> > > > + * Copyright (C) 2024 KylinSoft Corporation.
> > > > + */
> > > > +
> > > > +#include <linux/acpi.h>
> > > > +#include <linux/device.h>
> > > > +#include <linux/input.h>
> > > > +#include <linux/module.h>
> > > > +#include <linux/wmi.h>
> > > > +
> > > > +#define WMI_LENOVO_CAMERABUTTON_EVENT_GUID
> > > > "50C76F1F-D8E4-D895-0A3D-62F4EA400013"
> > > > +
> > > > +struct lenovo_wmi_priv {
> > > > +=09struct input_dev *idev;
> > > > +};
> > > > +
> > > > +enum {
> > > > +=09SW_CAMERA_OFF=09=3D 0,
> > > > +=09SW_CAMERA_ON=09=3D 1,
> > > > +};
> > > > +
> > > > +static void lenovo_wmi_notify(struct wmi_device *wdev, union
> > > > acpi_object
> > > > *obj)
> > > > +{
> > > > +=09struct lenovo_wmi_priv *priv =3D dev_get_drvdata(&wdev->dev);
> > > > +=09u8 camera_mode;
> > > > +
> > > > +=09if (obj->type !=3D ACPI_TYPE_BUFFER) {
> > > > +=09=09dev_err(&wdev->dev, "Bad response type %u\n", obj->type);
> > > > +=09=09return;
> > > > +=09}
> > > > +
> > > > +=09if (obj->buffer.length !=3D 1) {
> > > > +=09=09dev_err(&wdev->dev, "Invalid buffer length %u\n",
> > > > obj->buffer.length);
> > > > +=09=09return;
> > > > +=09}
> > > > +
> > > > +=09/* obj->buffer.pointer[0] is camera mode:
> > > > +=09 *      0 camera close
> > > > +=09 *      1 camera open
> > > > +=09 */
> > > > +=09camera_mode =3D obj->buffer.pointer[0];
> > > > +=09if (camera_mode > SW_CAMERA_ON) {
> > > > +=09=09dev_err(&wdev->dev, "Unknown camera mode %u\n", camera_mode)=
;
> > > > +=09=09return;
> > > > +=09}
> > > > +
> > > > +=09if (camera_mode =3D=3D SW_CAMERA_ON) {
> > > > +=09=09input_report_key(priv->idev, KEY_CAMERA_ACCESS_ENABLE, 1);
> > > > +=09=09input_sync(priv->idev);
> > > > +=09=09input_report_key(priv->idev, KEY_CAMERA_ACCESS_ENABLE, 0);
> > > > +=09} else {
> > > > +=09=09input_report_key(priv->idev, KEY_CAMERA_ACCESS_DISABLE, 1);
> > > > +=09=09input_sync(priv->idev);
> > > > +=09=09input_report_key(priv->idev, KEY_CAMERA_ACCESS_DISABLE, 0);
> > > > +=09}
> > While not exactly wrong the if seems unnecessary, you could do:
> >=20
> > =09unsigned int keycode;
> >=20
> > =09...
> >=20
> > =09keycode =3D camera_mode =3D=3D SW_CAMERA_ON ? KEY_CAMERA_ACCESS_ENAB=
LE :
> > =09=09=09=09=09=09KEY_CAMERA_ACCESS_DISABLE;
> >=20
> > =09input_report_key(priv->idev, keycode, 1);
> > =09input_sync(priv->idev);
> > =09input_report_key(priv->idev, keycode, 0);
> > > > +=09input_sync(priv->idev);
> > > > +}
> > Armin,
> >=20
> > I tried to figure out the concurrency rules for the WMI notify handler =
but
> > came up basically nothing. I suppose it boils down on ACPI notify handl=
ing
> > and I couldn't find useful documentation about that either. :-/
> >=20
> > Could you perhaps add this information into WMI documentation?
>=20
> As far as i know, the ACPI notify handlers can be scheduled concurrently =
on
> all CPUs,
> see https://lore.kernel.org/all/7617703.EvYhyI6sBW@kreacher/ for details.

Hi,

I meant this from the point of view whether the same notify handler can=20
only have one instance active at a time because otherwise one would=20
need locking to protect e.g. that input injection sequence.

> I will add a short note about this to the WMI driver guide which i plan t=
o
> upstream soon (after the EC handler stuff is finished).

Thanks.

--=20
 i.

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