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: <YgKJtjoFMSzxNiiI@sirena.org.uk>
Date:   Tue, 8 Feb 2022 15:18:14 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Javier Martinez Canillas <javierm@...hat.com>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux Fbdev development list <linux-fbdev@...r.kernel.org>,
        Linux PWM List <linux-pwm@...r.kernel.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Noralf Trønnes <noralf@...nnes.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Maxime Ripard <maxime@...no.tech>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, Lee Jones <lee.jones@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Sam Ravnborg <sam@...nborg.org>
Subject: Re: [PATCH v2 0/4] drm/tiny: Add driver for Solomon SSD1307 OLED
 displays

On Tue, Feb 08, 2022 at 04:10:49PM +0100, Javier Martinez Canillas wrote:
> On 2/8/22 15:19, Geert Uytterhoeven wrote:

> >   - "time ls" on the serial console (no files in the current directory,
> >     so nothing to print) increases from 0.86s to 1.92s, so the system is
> >     more loaded.  As ssd1307fb relied on deferred I/O too, the slowdown
> >     might be (partly) due to redrawing of the visual artefacts
> >     mentioned above.

> I was trying to first have the driver and then figure out how to optimize
> it. For v3 I'm using regmap to access instead of the I2C layer directly.

> I noticed that this is even slower but it makes the driver more clean and
> allows to support both I2C and SPI (untested but will include it as a WIP).

I wouldn't have expected regmap to add huge overhead relative to I2C,
partly predicated on I2C being rather slow itself.  There will be some
overhead for concurrency protection and data marshalling but for I2C
clocked at normal speeds it's surprising.

Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)

Powered by blists - more mailing lists