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]
Message-ID: <20180823131935.1eae184f@ipc1.ka-ro>
Date:   Thu, 23 Aug 2018 13:19:35 +0200
From:   Lothar Waßmann <LW@...O-electronics.de>
To:     Lukasz Majewski <lukma@...x.de>
Cc:     Michal Vokáč <michal.vokac@...ft.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        devicetree@...r.kernel.org, linux-pwm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Fabio Estevam <fabio.estevam@....com>
Subject: Re: [RFC PATCH 1/2] dt-bindings: pwm: imx: Allow switching PWM
 output between PWM and GPIO

Lukasz Majewski <lukma@...x.de> wrote:

> Hi Michal,
> 
> > Output of the PWM block of i.MX SoCs is always zero volts when the
> > block is disabled. This can caue issues when inverted PWM polarity is
> > needed. With inverted polarity a duty cycle = 0% corresponds to solid
> > high level on the output. If the PWM is dissabled its output
> > instantly goes to solid zero which corresponds to duty cycle = 100%.
> > 
> > To have a trully inverted PWM output configure the PWM pad as a GPIO
> > with pull-up. Then switch the pad to PWM output whenever non-zero
> > duty cycle is needed.  
> 
> Just to ask - Is your display equipped with power supply enable/disable
> pin?
> 
> As fair as I remember the trick to avoid flickering the display
> was to disable the display (enable-gpio property) and set the PWM PIN
> as GPIO to high in u-boot.
> 
Unfortunately there are both types of displays. Some with an ENABLE
pin, some without.


Lothar Waßmann
-- 
___________________________________________________________

Ka-Ro electronics GmbH | Pascalstraße 22 | D - 52076 Aachen
Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10
Geschäftsführer: Matthias Kaussen
Handelsregistereintrag: Amtsgericht Aachen, HRB 4996

www.karo-electronics.de | info@...o-electronics.de
___________________________________________________________

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ