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

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Date:	Mon, 29 Apr 2013 18:06:06 +0800
From:	joeyli <jlee@...e.com>
To:	Aaron Lu <aaron.lu@...el.com>
Cc:	mjg@...hat.com, rjw@...k.pl, platform-driver-x86@...r.kernel.org,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	Carlos Corbacho <carlos@...angeworlds.co.uk>,
	Dmitry Torokhov <dtor@...l.ru>,
	Corentin Chary <corentincj@...aif.net>,
	Thomas Renninger <trenn@...e.de>
Subject: Re: [PATCH 1/2] acpi: video: add function to support unregister
 backlight

於 五，2013-04-26 於 13:24 +0800，Aaron Lu 提到：
> On 04/22/2013 08:39 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
> >
> > 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);
> > +			}
> 
> The cooling_dev should also be unregistered I think.
> 
> Thanks,
> Aaron
> 

Yes, you are right!

Unregistering  backlight interface of video devices means the backlight
control functions broken, so it can not used for throttling.

I will unregister cooling_dev in v2 patch.


Thanks a lot!
Joey Lee

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