From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [PATCH v2 0/3] leds: blink resolution improvements Date: Thu, 30 Apr 2015 19:30:25 +0200 Message-ID: <20150430173024.GB21211@amd> References: <553E6CF5.4030601@list.ru> <20150427205441.GB1301@xo-6d-61-c0.localdomain> <553EA6B9.5040309@list.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <553EA6B9.5040309@list.ru> Sender: linux-kernel-owner@vger.kernel.org To: Stas Sergeev Cc: linux-leds@vger.kernel.org, Linux kernel , Stas Sergeev List-Id: linux-leds@vger.kernel.org Hi! > >>The following patches improve the precision of led > >>timer trigger and add the delay unit control. > >>That allows to make PWM brightness control with timer > >>trigger. > >Are you sure that is good idea? Doing LED pwm with main cpu is quite harsh... > Do you remember the pc-speaker driver? :) Actually yes, I do, and that one has the same interface as "normal" sound cards. > For the timer trigger I would pretty much like my approach to stay. > The reason is that the PWM I need to do, is not strictly a PWM - > it needs the ON period in range of tens or hundreds of milliseconds, > while the OFF period is in a couple of usecs (or vice-versa). No That is a PWM, right? I see why you'd want to have short "on", but I don't see why you'd want short "off"... There's one thing you have to do: having two files, one specifiying units and second one specifying timeout is not going to work. What about simply "echo 0.001 > delay_on"? Thanks, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html