From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 0F2BC83D for ; Thu, 28 Jul 2016 22:15:29 +0000 (UTC) Received: from saturn.retrosnub.co.uk (saturn.retrosnub.co.uk [178.18.118.26]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 4D3151A2 for ; Thu, 28 Jul 2016 22:15:28 +0000 (UTC) To: Laurent Pinchart , ksummit-discuss@lists.linuxfoundation.org References: <5222c3bb-d6b7-0ccc-bf9e-becf5046a37a@kernel.org> <20160728085846.63971233@recife.lan> <1509685.ufIZn1R9J2@avalon> From: Jonathan Cameron Message-ID: <8fee553b-de04-27c9-9c33-d578a1f3cca1@jic23.retrosnub.co.uk> Date: Thu, 28 Jul 2016 23:09:59 +0100 MIME-Version: 1.0 In-Reply-To: <1509685.ufIZn1R9J2@avalon> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: Zhang Rui , Rob Herring Subject: Re: [Ksummit-discuss] [TECH TOPIC] Sensors and similar - subsystem interactions, divisions, bindings etc. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 28/07/16 17:42, Laurent Pinchart wrote: > On Thursday 28 Jul 2016 08:58:46 Mauro Carvalho Chehab wrote: >> Em Wed, 20 Jul 2016 22:18:11 +0100 Jonathan Cameron escreveu: >>> Hi All, >>> >>> This topic would be around the way the various subsystems interact, in the >>> rough area of 'sensors' (I haven't yet had much of an issue with subsystem >>> crossing with output devices but maybe that's just over the next hill!) >> >> Yeah, there is a gray area here as devices become more complex. >> So, I'm interested on such topic. >> >>> Scope may well be wider but includes: >>> * input (some of it) >>> * hwmon >>> * iio >>> * comedi(?) >>> * thermal >>> * power/battery >>> * gpio - the blur between gpios and beaglescope / PLC type I/O. >>> * v4l - when does a device jump from being a multi pixel thermopile >>> to a thermal camera? Smart fingerprint scanners etc. Gesture recognition >>> sensors (effectively 9ish pixel cameras) >> >> For devices that provide images somehow, I'd say that the best would be >> to implement them as via the V4L2 API. > > This requires defining what an image is. Furthermore, we very low image > resolution devices, we will need to deal with high frame rates (1k-10k is a > range we need to consider). The V4L2 API will likely show performance issues. An interesting point I'd never thought about before. Funnily enough the devices around this boundary that I've encountered have all been relatively slow. Doubt we'll be lucky enough that that will last! Jonathan > >> We'll likely need to discuss it case by case, specially for early cross- >> subsystem drivers, though, as it is not trivial to identify the subsystem >> boundaries, and sometimes multiple APIs from different subsystems is needed. >> Also, it is not clear where such drivers would fit at the Kernel tree. >> >> One interesting case is an input device driver with multi-finger >> support (drivers/input/touchscreen/sur40.c). I suspect we'll have >> more cases like that over time. >> >>> * Lots of random things we haven't seen yet. >