linux-kernel - Re: [PATCH v4 2/6] input: touchscreen: ti_am335x

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Date:	Sat, 15 Nov 2014 20:27:39 +0100
From:	Richard Cochran <richardcochran@...il.com>
To:	Vignesh R <vigneshr@...com>
Cc:	Rob Herring <robh+dt@...nel.org>, Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Benoit Cousson <bcousson@...libre.com>,
	Tony Lindgren <tony@...mide.com>,
	Russell King <linux@....linux.org.uk>,
	Jonathan Cameron <jic23@...nel.org>,
	Hartmut Knaack <knaack.h@....de>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Lee Jones <lee.jones@...aro.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Peter Meerwald <pmeerw@...erw.net>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Felipe Balbi <balbi@...com>, Brad Griffis <bgriffis@...com>,
	Sanjeev Sharma <sanjeev_sharma@...tor.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Jan Kardell <jan.kardell@...liq.com>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-iio@...r.kernel.org, linux-input@...r.kernel.org
Subject: Re: [PATCH v4 2/6] input: touchscreen: ti_am335x_tsc: Remove udelay
 in interrupt handler

On Fri, Nov 14, 2014 at 10:37:27AM +0530, Vignesh R wrote:
> From: Brad Griffis <bgriffis@...com>
> 
> TSC interrupt handler had udelay to avoid reporting of false pen-up
> interrupt to user space. This patch implements workaround suggesting in
> Advisory 1.0.31 of silicon errata for am335x, thus eliminating udelay
> and touchscreen lag. This also improves performance of touchscreen and
> eliminates sudden jump of cursor at touch release.

I back ported this series onto v3.15.1 in order to try this out on a
custom, beaglebone-like board. With this series, the touch is really
broken. (I had fixed the pen up problem in a totally different way for
a customer, and so I wanted to try out your solution.)

I will try to port the board code to a more recent kernel to try your
series again. With which kernel version did you test your patches?

And which board?

Thanks,
Richard


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