linux-kernel - Re: [PATCH v4 1/4] backlight: introduce backlight_device

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 10 Oct 2013 08:23:02 +0300
From:	Jani Nikula <jani.nikula@...ux.intel.com>
To:	Aaron Lu <aaron.lu@...el.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	linux-acpi@...r.kernel.org, intel-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	Daniel Vetter <daniel@...ll.ch>,
	Matthew Garrett <matthew.garrett@...ula.com>,
	Seth Forshee <seth.forshee@...onical.com>,
	Lee Chun-Yi <joeyli.kernel@...il.com>,
	Richard Purdie <rpurdie@...ys.net>,
	Igor Gnatenko <i.gnatenko.brain@...il.com>,
	Yves-Alexis Perez <corsac@...ian.org>,
	Felipe Contreras <felipe.contreras@...il.com>,
	Ben Jencks <ben@...ncks.net>,
	Steven Newbury <steve@...wbury.org.uk>,
	James Hogan <james@...anarts.com>,
	Kamal Mostafa <kamal@...onical.com>,
	Joerg Platte <jplatte@...sa.net>,
	Kalle Valo <kvalo@...rom.com>,
	Martin Steigerwald <Martin@...htvoll.de>,
	Jörg Otte <jrg.otte@...il.com>,
	Mike Galbraith <bitbucket@...ine.de>,
	platform-driver-x86@...r.kernel.org,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Henrique de Moraes Holschuh <hmh@....eng.br>
Subject: Re: [PATCH v4 1/4] backlight: introduce backlight_device_registered

On Thu, 10 Oct 2013, Aaron Lu <aaron.lu@...el.com> wrote:
> On 10/10/2013 12:29 PM, Jani Nikula wrote:
>> On Thu, 10 Oct 2013, Aaron Lu <aaron.lu@...el.com> wrote:
>>> On 10/10/2013 08:25 AM, Rafael J. Wysocki wrote:
>>>> On Tuesday, October 08, 2013 02:39:58 PM Aaron Lu wrote:
>>>>> +bool backlight_device_registered(enum backlight_type type)
>>>>> +{
>>>>> +	bool found = false;
>>>>> +	struct backlight_device *bd;
>>>>> +
>>>>> +	mutex_lock(&bd_list_mutex);
>>>>> +	list_for_each_entry(bd, &bd_list_head, entry) {
>>>>> +		if (bd->props.type == type) {
>>>>> +			found = true;
>>>>> +			break;
>>>>> +		}
>>>>> +	}
>>>>
>>>> Isn't it useful to be able to register more than one backlight device of the
>>>> same type sometimes?
>>>
>>> I think so for some kind of computers. OTOH, the above function should
>>> be enough for the problem we are solving here, if someday we need to
>>> differentiate, we can enhance the code then.
>> 
>> Since both Baytrail and Haswell already have two backlight PWMs, this
>> may be needed sooner than you think. But we shouldn't let that block
>
> Do we need to differentiate which backlight PWM is registered to decide
> if ACPI video backlight interface should be skipped? My understanding is
> no.

That's correct. If things change, we can fix it then.

Jani.


>
> Thanks,
> Aaron
>
>> fixing the more urgent issue we have now. So I'm fine with this. It
>> doesn't prevent one from registering more than one device of the same
>> type anyway.
>> 
>> BR,
>> Jani.
>> 
>> 
>> 
>

-- 
Jani Nikula, Intel Open Source Technology Center
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/