linux-kernel - Re: [PATCH v2 2/2] Input: ads7846: convert to one message

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] [day] [month] [year] [list]

Message-ID: <YAksInM07b3ACwMa@google.com>
Date:   Wed, 20 Jan 2021 23:24:18 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Oleksij Rempel <o.rempel@...gutronix.de>
Cc:     Alexandru Ardelean <alexandru.ardelean@...log.com>,
        Mark Brown <broonie@...nel.org>, kernel@...gutronix.de,
        linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
        linux-spi@...r.kernel.org, David Jander <david@...tonic.nl>
Subject: Re: [PATCH v2 2/2] Input: ads7846: convert to one message

On Wed, Jan 20, 2021 at 08:40:32AM +0100, Oleksij Rempel wrote:
> 
> Hi Dmitry,
> 
> On Tue, Nov 17, 2020 at 04:31:38PM -0800, Dmitry Torokhov wrote:
> > On Tue, Nov 10, 2020 at 09:50:41AM +0100, Oleksij Rempel wrote:
> > > Convert multiple full duplex transfers in to a single transfer to reduce
> > > CPU load.
> > > 
> > > Current driver version support following filtering modes:
> > > - ads7846_no_filter() - not filtered
> > > - ads7846_debounce_filter() - driver specific debounce filter
> > > - pdata->filter - platform specific debounce filter (do any platform
> > > 	provides such filter?)
> > > 
> > > Without filter this HW is not really usable, since the physic of
> > > resistive touchscreen can provide some bounce effects. With driver internal
> > > filter, we have constant amount of retries + debounce retries if some anomaly
> > > was detected.
> > > 
> > > High amount of tiny SPI transfers is the primer reason of high CPU load
> > > and interrupt frequency.
> > > 
> > > This patch create one SPI transfer with all fields and not optional retires. If
> > > bounce anomaly was detected, we will make more transfer if needed.
> > > 
> > > Without this patch, we will get about 10% CPU load on iMX6S on pen-down event.
> > > For example by holding stylus on the screen.
> > > 
> > > With this patch, depending in the amount of retries, the CPU load will
> > > be 1% with "ti,debounce-rep = <3>".
> > > 
> > > One buffer transfer allows us to use PIO FIFO or DMA engine, depending
> > > on the platform.
> > > 
> > > Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
> > 
> > Applied, thank you.
> 
> I can't find this patch in your git repository. Should I rebase it
> against latest git and resend it?

Ugh, sorry, now applied for realz.

Thanks.

-- 
Dmitry