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Date: Fri, 15 Mar 2024 19:54:22 +0200 (EET)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Armin Wolf <W_Armin@....de>
cc: Ai Chao <aichao@...inos.cn>, Hans de Goede <hdegoede@...hat.com>,
LKML <linux-kernel@...r.kernel.org>, platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH v8] platform/x86: add lenovo wmi camera button driver
On Fri, 15 Mar 2024, Armin Wolf wrote:
> Am 15.03.24 um 12:51 schrieb Ilpo Järvinen:
> > On Thu, 14 Mar 2024, Armin Wolf wrote:
> > > Am 14.03.24 um 06:03 schrieb Ai Chao:
> > >
> > > > Add lenovo generic wmi driver to support camera button.
> > > > The Camera button is a GPIO device. This driver receives ACPI notifyi
> > > > when the camera button is switched on/off. This driver is used in
> > > > Lenovo A70, it is a Computer integrated machine.
> > > >
> > > > Signed-off-by: Ai Chao <aichao@...inos.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.
> > > >
> > > > 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
> > > >
> > > > diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> > > > index bdd302274b9a..9506a455b547 100644
> > > > --- a/drivers/platform/x86/Kconfig
> > > > +++ b/drivers/platform/x86/Kconfig
> > > > @@ -1001,6 +1001,18 @@ config INSPUR_PLATFORM_PROFILE
> > > > To compile this driver as a module, choose M here: the module
> > > > will be called inspur-platform-profile.
> > > >
> > > > +config LENOVO_WMI_CAMERA
> > > > + tristate "Lenovo WMI Camera Button driver"
> > > > + depends on ACPI_WMI
> > > > + depends on INPUT
> > > > + help
> > > > + This driver provides support for Lenovo camera button. The Camera
> > > > + button is a GPIO device. This driver receives ACPI notify when the
> > > > + camera button is switched on/off.
> > > > +
> > > > + To compile this driver as a module, choose M here: the module
> > > > + will be called lenovo-wmi-camera.
> > > > +
> > > > source "drivers/platform/x86/x86-android-tablets/Kconfig"
> > > >
> > > > 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-$(CONFIG_SENSORS_HDAPS) += hdaps.o
> > > > obj-$(CONFIG_THINKPAD_ACPI) += thinkpad_acpi.o
> > > > obj-$(CONFIG_THINKPAD_LMI) += think-lmi.o
> > > > obj-$(CONFIG_YOGABOOK) += lenovo-yogabook.o
> > > > +obj-$(CONFIG_LENOVO_WMI_CAMERA) += lenovo-wmi-camera.o
> > > >
> > > > # Intel
> > > > obj-y += 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@...inos.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 {
> > > > + struct input_dev *idev;
> > > > +};
> > > > +
> > > > +enum {
> > > > + SW_CAMERA_OFF = 0,
> > > > + SW_CAMERA_ON = 1,
> > > > +};
> > > > +
> > > > +static void lenovo_wmi_notify(struct wmi_device *wdev, union
> > > > acpi_object
> > > > *obj)
> > > > +{
> > > > + struct lenovo_wmi_priv *priv = dev_get_drvdata(&wdev->dev);
> > > > + u8 camera_mode;
> > > > +
> > > > + if (obj->type != ACPI_TYPE_BUFFER) {
> > > > + dev_err(&wdev->dev, "Bad response type %u\n", obj->type);
> > > > + return;
> > > > + }
> > > > +
> > > > + if (obj->buffer.length != 1) {
> > > > + dev_err(&wdev->dev, "Invalid buffer length %u\n",
> > > > obj->buffer.length);
> > > > + return;
> > > > + }
> > > > +
> > > > + /* obj->buffer.pointer[0] is camera mode:
> > > > + * 0 camera close
> > > > + * 1 camera open
> > > > + */
> > > > + camera_mode = obj->buffer.pointer[0];
> > > > + if (camera_mode > SW_CAMERA_ON) {
> > > > + dev_err(&wdev->dev, "Unknown camera mode %u\n", camera_mode);
> > > > + return;
> > > > + }
> > > > +
> > > > + if (camera_mode == SW_CAMERA_ON) {
> > > > + input_report_key(priv->idev, KEY_CAMERA_ACCESS_ENABLE, 1);
> > > > + input_sync(priv->idev);
> > > > + input_report_key(priv->idev, KEY_CAMERA_ACCESS_ENABLE, 0);
> > > > + } else {
> > > > + input_report_key(priv->idev, KEY_CAMERA_ACCESS_DISABLE, 1);
> > > > + input_sync(priv->idev);
> > > > + input_report_key(priv->idev, KEY_CAMERA_ACCESS_DISABLE, 0);
> > > > + }
> > While not exactly wrong the if seems unnecessary, you could do:
> >
> > unsigned int keycode;
> >
> > ...
> >
> > keycode = camera_mode == SW_CAMERA_ON ? KEY_CAMERA_ACCESS_ENABLE :
> > KEY_CAMERA_ACCESS_DISABLE;
> >
> > input_report_key(priv->idev, keycode, 1);
> > input_sync(priv->idev);
> > input_report_key(priv->idev, keycode, 0);
> > > > + input_sync(priv->idev);
> > > > +}
> > Armin,
> >
> > 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 handling
> > and I couldn't find useful documentation about that either. :-/
> >
> > Could you perhaps add this information into WMI documentation?
>
> 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
only have one instance active at a time because otherwise one would
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 to
> upstream soon (after the EC handler stuff is finished).
Thanks.
--
i.
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