From patchwork Wed Dec 24 07:03:37 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vignesh Raghavendra X-Patchwork-Id: 5536591 Return-Path: X-Original-To: patchwork-linux-omap@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 8C2BF9F1CD for ; Wed, 24 Dec 2014 07:07:03 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 9F883201C0 for ; Wed, 24 Dec 2014 07:07:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4D279201B9 for ; Wed, 24 Dec 2014 07:07:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751564AbaLXHGI (ORCPT ); Wed, 24 Dec 2014 02:06:08 -0500 Received: from comal.ext.ti.com ([198.47.26.152]:33131 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751576AbaLXHF4 (ORCPT ); Wed, 24 Dec 2014 02:05:56 -0500 Received: from dflxv15.itg.ti.com ([128.247.5.124]) by comal.ext.ti.com (8.13.7/8.13.7) with ESMTP id sBO753HM010863; Wed, 24 Dec 2014 01:05:03 -0600 Received: from DFLE73.ent.ti.com (dfle73.ent.ti.com [128.247.5.110]) by dflxv15.itg.ti.com (8.14.3/8.13.8) with ESMTP id sBO752oV026759; Wed, 24 Dec 2014 01:05:03 -0600 Received: from dflp33.itg.ti.com (10.64.6.16) by DFLE73.ent.ti.com (128.247.5.110) with Microsoft SMTP Server id 14.3.174.1; Wed, 24 Dec 2014 01:05:02 -0600 Received: from uda0132425.apr.dhcp.ti.com (ileax41-snat.itg.ti.com [10.172.224.153]) by dflp33.itg.ti.com (8.14.3/8.13.8) with ESMTP id sBO74Mhn005006; Wed, 24 Dec 2014 01:04:55 -0600 From: Vignesh R To: Jonathan Cameron , Hartmut Knaack , Dmitry Torokhov , Lee Jones , Sebastian Andrzej Siewior CC: Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Benoit Cousson , Tony Lindgren , Russell King , Lars-Peter Clausen , Peter Meerwald , Samuel Ortiz , Brad Griffis , Paul Gortmaker , Sanjeev Sharma , Jan Kardell , Felipe Balbi , Wolfram Sang , , , , , , , Vignesh R Subject: [PATCH v5 4/6] ARM: dts: AM335x: Make charge delay a DT parameter for TSC Date: Wed, 24 Dec 2014 12:33:37 +0530 Message-ID: <1419404619-10744-5-git-send-email-vigneshr@ti.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1419404619-10744-1-git-send-email-vigneshr@ti.com> References: <1419404619-10744-1-git-send-email-vigneshr@ti.com> MIME-Version: 1.0 Sender: linux-omap-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The charge delay value is by default 0x400. But it can be set to lower values on some boards, as long as false pen-ups are avoided. Lowering the value increases the sampling rate (though current sampling rate is sufficient for TSC operation). In some boards, the value has to be increased to avoid false pen-up events. Hence, charge delay has been made a DT parameter. Signed-off-by: Vignesh R Acked-by: Tony Lindgren --- v4: - Set charge delay to 0x400 as default. Most devices function normally at this value .../devicetree/bindings/input/touchscreen/ti-tsc-adc.txt | 15 +++++++++++++++ arch/arm/boot/dts/am335x-evm.dts | 1 + 2 files changed, 16 insertions(+) diff --git a/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt b/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt index 878549ba814d..6df5028a4ad3 100644 --- a/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt +++ b/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt @@ -28,6 +28,20 @@ Required properties: ti,adc-channels: List of analog inputs available for ADC. AIN0 = 0, AIN1 = 1 and so on till AIN7 = 7. +Optional properties: +- child "tsc" + ti,charge-delay: Length of touch screen charge delay step in terms of + ADC clock cycles. Charge delay value should be large + in order to avoid false pen-up events. This value + affects the overall sampling speed, hence need to be + kept as low as possible, while avoiding false pen-up + event. Start from a lower value, say 0x400, and + increase value until false pen-up events are avoided. + The pen-up detection happens immediately after the + charge step, so this does in fact function as a + hardware knob for adjusting the amount of "settling + time". + Example: tscadc: tscadc@44e0d000 { compatible = "ti,am3359-tscadc"; @@ -36,6 +50,7 @@ Example: ti,x-plate-resistance = <200>; ti,coordiante-readouts = <5>; ti,wire-config = <0x00 0x11 0x22 0x33>; + ti,charge-delay = <0x400>; }; adc { diff --git a/arch/arm/boot/dts/am335x-evm.dts b/arch/arm/boot/dts/am335x-evm.dts index 54f118c08db8..66342515df20 100644 --- a/arch/arm/boot/dts/am335x-evm.dts +++ b/arch/arm/boot/dts/am335x-evm.dts @@ -648,6 +648,7 @@ ti,x-plate-resistance = <200>; ti,coordinate-readouts = <5>; ti,wire-config = <0x00 0x11 0x22 0x33>; + ti,charge-delay = <0x400>; }; adc {