From mboxrd@z Thu Jan  1 00:00:00 1970
From: Hans de Goede <hdegoede@redhat.com>
Subject: Re: [PATCH v5 2/6] leds: triggers: Add a keyboard backlight trigger
Date: Thu, 24 Nov 2016 10:21:43 +0100
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To: =?UTF-8?Q?Pali_Roh=c3=a1r?= <pali.rohar@gmail.com>, Jacek Anaszewski <j.anaszewski@samsung.com>
Cc: gdg@zplane.com, Pavel Machek <pavel@ucw.cz>, Jacek Anaszewski <jacek.anaszewski@gmail.com>, Darren Hart <dvhart@infradead.org>, Matthew Garrett <mjg59@srcf.ucam.org>, Henrique de Moraes Holschuh <ibm-acpi@hmh.eng.br>, Richard Purdie <rpurdie@rpsys.net>, ibm-acpi-devel@lists.sourceforge.net, platform-driver-x86@vger.kernel.org, linux-leds@vger.kernel.org

Hi Pali,

On 24-11-16 10:15, Pali Rohár wrote:
> On Wednesday 23 November 2016 12:01:02 Jacek Anaszewski wrote:
>> I would also appreciate your opinion on the other solution to the
>> problem of notifying brightness changes originating from hardware,
>> i.e. hw_brightness_change{_ro} file, that would support POLLPRI events,
>> and reading brightness.
>
> Another idea:
>
> If no trigger is active then led subsystem will invoke POLLPRI on
> "brightness" sysfs file.
>
> And if there is active trigger then only trigger code could invoke
> POLLPRI on "brightness" file.
>
> This could solve problem with high CPU load and power usage when e.g.
> cpu trigger is active (and cpu trigger will not implement any POLLPRI).
>
> Do not know if this is really enough for your situation, it is just and
> another idea.
>
> But first please update documentation in ABI/testing to match current
> situation. That is really needed.

Patches are welcome ...     :)

Regards,

Hans