From: Oleksij Rempel <o.rempel@pengutronix.de>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Alexandru Ardelean <alexandru.ardelean@analog.com>,
Mark Brown <broonie@kernel.org>,
kernel@pengutronix.de, linux-kernel@vger.kernel.org,
linux-input@vger.kernel.org, linux-spi@vger.kernel.org,
David Jander <david@protonic.nl>
Subject: Re: [PATCH v2 2/2] Input: ads7846: convert to one message
Date: Wed, 20 Jan 2021 08:40:32 +0100 [thread overview]
Message-ID: <20210120074032.2swvp7iqli6xttul@pengutronix.de> (raw)
In-Reply-To: <20201118003138.GD2009714@dtor-ws>
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@pengutronix.de>
>
> Applied, thank you.
I can't find this patch in your git repository. Should I rebase it
against latest git and resend it?
Regards,
Oleksij
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next prev parent reply other threads:[~2021-01-20 7:42 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-10 8:50 [PATCH v1 0/2] Input: ads7846: reduce SPI related CPU load Oleksij Rempel
2020-11-10 8:50 ` [PATCH v2 1/2] Input: ads7846: convert to full duplex Oleksij Rempel
2020-11-18 0:31 ` Dmitry Torokhov
2020-11-10 8:50 ` [PATCH v2 2/2] Input: ads7846: convert to one message Oleksij Rempel
2020-11-18 0:31 ` Dmitry Torokhov
2021-01-20 7:40 ` Oleksij Rempel [this message]
2021-01-21 7:24 ` Dmitry Torokhov
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