From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailout2.samsung.com ([203.254.224.25]:57411 "EHLO mailout2.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751131AbdINNQh (ORCPT ); Thu, 14 Sep 2017 09:16:37 -0400 Subject: Re: as3645a flash userland interface To: Pavel Machek Cc: Jacek Anaszewski , Sakari Ailus , linux-leds@vger.kernel.org, linux-media@vger.kernel.org, niklas.soderlund@ragnatech.se, robh@kernel.org, hverkuil@xs4all.nl, laurent.pinchart@ideasonboard.com, devicetree@vger.kernel.org, sre@kernel.org From: Sylwester Nawrocki Message-id: <82a4a519-e402-8eae-0352-e3e287fc508f@samsung.com> Date: Thu, 14 Sep 2017 15:16:29 +0200 MIME-version: 1.0 In-reply-to: <20170914115323.GA1850@amd> Content-type: text/plain; charset="windows-1252"; format="flowed" Content-language: en-GB Content-transfer-encoding: 7bit References: <20170912084236.1154-1-sakari.ailus@linux.intel.com> <20170912084236.1154-25-sakari.ailus@linux.intel.com> <20170912103628.GB27117@amd> <7b679cb3-ce58-e1d1-60bf-995896bf46eb@gmail.com> <20170912215529.GA17218@amd> <21824758-28a1-7007-6db5-86a900025d14@gmail.com> <4bf12e8e-beff-0199-cdee-4a52ebe7cdaf@samsung.com> <20170914100718.GA3843@amd> <1f34a891-edb1-251c-86a8-ba4a90c485d3@samsung.com> <20170914115323.GA1850@amd> Sender: linux-media-owner@vger.kernel.org List-ID: On 09/14/2017 01:53 PM, Pavel Machek wrote: > On Thu 2017-09-14 13:01:19, Sylwester Nawrocki wrote: >> On 09/14/2017 12:07 PM, Pavel Machek wrote: >>>> Isn't the V4L2 subdev/Media Controller API supposed to provide means >>>> for associating flash LEDs with camera sensors? You seem to be insisting >>>> on using the sysfs leds interface for that, which is not a primary >>>> interface for camera flash AFAICT. >>> >>> a) subdev/media controller API currently does not provide such means. >> >> Yes, but it should, that's what it was designed for AFAIK. >> >>> b) if we have /sys/class/leds interface to userland, it should be >>> useful. >> >> At the same time we shouldn't overcomplicate it with the camera >> functionality. > > I'm advocating adding label = "main_camera" into the .dts. That's all. > >>> c) having flashlight application going through media controller API is >>> a bad joke. >> >> It doesn't have to, maybe I misunderstood what you exactly ask for. >> Nevertheless what's missing is some user visible name/label for each >> flash LED, right? Currently enumerating flash LEDs can be done by looking >> at the function part of /sys/class/leds/:: >> path. >> >> Could additional information be appended to the part, so >> user can identify which LED is which? E.g. "flash(rear)", "flash(front)", >> etc. This could be achieved by simply adding label property in DT. >> Or is the list of supported strings already standardized? > > label = "flash_main_camera" would work for me, yes. And yes, I'd > prefer to do this before 4.14 release, so that userland-visible > interface does not change. Looking at existing label entries in DT (git grep label.*led -- arch/arm/boot/dts | sed 's\^.*label\label\' | sort | uniq) I can't see why something like this couldn't be added. Or label = "as3645a::flash_main_camera" so we abide the LED device naming rules described in Documentation/leds/leds-class.txt. -- Regards, Sylwester