linux-kernel - Re: [PATCH 1/2] acpi: video: add function to support unregister backlight

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Message-ID: <1608295.QCMETqCo7o@vostro.rjw.lan>
Date:	Tue, 23 Apr 2013 01:09:33 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Chun-Yi Lee <joeyli.kernel@...il.com>,
	Zhang Rui <rui.zhang@...el.com>
Cc:	mjg@...hat.com, platform-driver-x86@...r.kernel.org,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	"Lee, Chun-Yi" <jlee@...e.com>,
	Carlos Corbacho <carlos@...angeworlds.co.uk>,
	Dmitry Torokhov <dtor@...l.ru>,
	Corentin Chary <corentincj@...aif.net>,
	Aaron Lu <aaron.lu@...el.com>, Thomas Renninger <trenn@...e.de>
Subject: Re: [PATCH 1/2] acpi: video: add function to support unregister backlight

On Monday, April 22, 2013 08:39:15 PM Chun-Yi Lee wrote:
> From: "Lee, Chun-Yi" <jlee@...e.com>
> 
> There have situation we unregister whole acpi/video driver by downstream driver
> just want to remove backlight control interface of acpi/video. It caues we lost
> other functions of acpi/video, e.g. transfer acpi event to input event.
> 
> So, this patch add a new function, find_video_unregister_backlight, it provide
> the interface let downstream driver can tell acpi/video to unregister backlight
> interface of all acpi video devices. Then we can keep functions of acpi/video
> but only remove backlight support.
> 
> Reference: bko#35622
>         https://bugzilla.kernel.org/show_bug.cgi?id=35622

Rui, any comments?

Rafael


> Tested-by: Andrzej Krentosz <endrjux@...il.com>
> Cc: Carlos Corbacho <carlos@...angeworlds.co.uk>
> Cc: Matthew Garrett <mjg@...hat.com>
> Cc: Dmitry Torokhov <dtor@...l.ru>
> Cc: Corentin Chary <corentincj@...aif.net>
> Cc: Rafael J. Wysocki <rjw@...k.pl>
> Cc: Aaron Lu <aaron.lu@...el.com>
> Cc: Thomas Renninger <trenn@...e.de>
> Signed-off-by: Lee, Chun-Yi <jlee@...e.com>
> ---
>  drivers/acpi/video.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
>  include/acpi/video.h |  2 ++
>  2 files changed, 48 insertions(+)
> 
> diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
> index 313f959..acd2e7a 100644
> --- a/drivers/acpi/video.c
> +++ b/drivers/acpi/video.c
> @@ -1793,6 +1793,52 @@ static int __init intel_opregion_present(void)
>  	return opregion;
>  }
>  
> +static acpi_status
> +find_video_unregister_backlight(acpi_handle handle, u32 lvl, void *context,
> +				void **rv)
> +{
> +	struct acpi_device *acpi_dev;
> +	struct acpi_video_bus *video = NULL;
> +	struct acpi_video_device *dev, *next;
> +
> +	if (acpi_bus_get_device(handle, &acpi_dev))
> +		return AE_OK;
> +
> +	if (!acpi_match_device_ids(acpi_dev, video_device_ids)) {
> +		video = acpi_driver_data(acpi_dev);
> +		acpi_video_bus_stop_devices(video);
> +		mutex_lock(&video->device_list_lock);
> +		list_for_each_entry_safe(dev, next, &video->video_device_list,
> +					entry) {
> +			if (dev->backlight) {
> +				backlight_device_unregister(dev->backlight);
> +				dev->backlight = NULL;
> +				kfree(dev->brightness->levels);
> +				kfree(dev->brightness);
> +			}
> +		}
> +		mutex_unlock(&video->device_list_lock);
> +		acpi_video_bus_start_devices(video);
> +	}
> +	return AE_OK;
> +}
> +
> +void acpi_video_backlight_unregister(void)
> +{
> +	if (!register_count) {
> +		/*
> +		 * If the acpi video bus is already unloaded, don't
> +		 * unregister backlight of devices and return directly.
> +		 */
> +		return;
> +	}
> +	acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
> +			    ACPI_UINT32_MAX, find_video_unregister_backlight,
> +			    NULL, NULL, NULL);
> +	return;
> +}
> +EXPORT_SYMBOL(acpi_video_backlight_unregister);
> +
>  int acpi_video_register(void)
>  {
>  	int result = 0;
> diff --git a/include/acpi/video.h b/include/acpi/video.h
> index 61109f2..1e810a1 100644
> --- a/include/acpi/video.h
> +++ b/include/acpi/video.h
> @@ -19,11 +19,13 @@ struct acpi_device;
>  #if (defined CONFIG_ACPI_VIDEO || defined CONFIG_ACPI_VIDEO_MODULE)
>  extern int acpi_video_register(void);
>  extern void acpi_video_unregister(void);
> +extern void acpi_video_backlight_unregister(void);
>  extern int acpi_video_get_edid(struct acpi_device *device, int type,
>  			       int device_id, void **edid);
>  #else
>  static inline int acpi_video_register(void) { return 0; }
>  static inline void acpi_video_unregister(void) { return; }
> +static inline void acpi_video_backlight_unregister(void) { return; }
>  static inline int acpi_video_get_edid(struct acpi_device *device, int type,
>  				      int device_id, void **edid)
>  {
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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