From patchwork Wed Dec 24 07:03:39 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vignesh Raghavendra X-Patchwork-Id: 5536561 Return-Path: X-Original-To: patchwork-linux-omap@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id A0A86BEEA8 for ; Wed, 24 Dec 2014 07:06:45 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id BA1AE201C0 for ; Wed, 24 Dec 2014 07:06:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A7285201B9 for ; Wed, 24 Dec 2014 07:06:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751798AbaLXHG2 (ORCPT ); Wed, 24 Dec 2014 02:06:28 -0500 Received: from devils.ext.ti.com ([198.47.26.153]:45367 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751440AbaLXHGX (ORCPT ); Wed, 24 Dec 2014 02:06:23 -0500 Received: from dflxv15.itg.ti.com ([128.247.5.124]) by devils.ext.ti.com (8.13.7/8.13.7) with ESMTP id sBO75JN9020231; Wed, 24 Dec 2014 01:05:19 -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 sBO75JBT027122; Wed, 24 Dec 2014 01:05:19 -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 01:05:18 -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 sBO74Mhp005006; Wed, 24 Dec 2014 01:05:11 -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 6/6] input: touchscreen: ti_am335x_tsc: Replace delta filtering with median filtering Date: Wed, 24 Dec 2014 12:33:39 +0530 Message-ID: <1419404619-10744-7-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 Previously, delta filtering was applied TSC co-ordinate readouts before reporting a single value to user space. This patch replaces delta filtering with median filtering. Median filtering sorts co-ordinate readouts, drops min and max values, and reports the average of remaining values. This method is more sensible than delta filering. Median filtering is applied only if number of readouts is greater than 3 else just average of co-ordinate readouts is reported. Signed-off-by: Vignesh R --- drivers/input/touchscreen/ti_am335x_tsc.c | 91 +++++++++++++++++-------------- 1 file changed, 51 insertions(+), 40 deletions(-) diff --git a/drivers/input/touchscreen/ti_am335x_tsc.c b/drivers/input/touchscreen/ti_am335x_tsc.c index 9cb8b4a01dca..504b85db6425 100644 --- a/drivers/input/touchscreen/ti_am335x_tsc.c +++ b/drivers/input/touchscreen/ti_am335x_tsc.c @@ -26,6 +26,7 @@ #include #include #include +#include #include @@ -204,56 +205,61 @@ static void titsc_step_config(struct titsc *ts_dev) am335x_tsc_se_set_cache(ts_dev->mfd_tscadc, ts_dev->step_mask); } +static int titsc_cmp_coord(const void *a, const void *b) +{ + return *(int *)a - *(int *)b; +} + static void titsc_read_coordinates(struct titsc *ts_dev, u32 *x, u32 *y, u32 *z1, u32 *z2) { - unsigned int fifocount = titsc_readl(ts_dev, REG_FIFO0CNT); - unsigned int prev_val_x = ~0, prev_val_y = ~0; - unsigned int prev_diff_x = ~0, prev_diff_y = ~0; - unsigned int read, diff; - unsigned int i, channel; + unsigned int yvals[7], xvals[7]; + unsigned int i, xsum = 0, ysum = 0; unsigned int creads = ts_dev->coordinate_readouts; - unsigned int first_step = TOTAL_STEPS - (creads * 2 + 2); - *z1 = *z2 = 0; - if (fifocount % (creads * 2 + 2)) - fifocount -= fifocount % (creads * 2 + 2); - /* - * Delta filter is used to remove large variations in sampled - * values from ADC. The filter tries to predict where the next - * coordinate could be. This is done by taking a previous - * coordinate and subtracting it form current one. Further the - * algorithm compares the difference with that of a present value, - * if true the value is reported to the sub system. - */ - for (i = 0; i < fifocount; i++) { - read = titsc_readl(ts_dev, REG_FIFO0); - - channel = (read & 0xf0000) >> 16; - read &= 0xfff; - if (channel > first_step + creads + 2) { - diff = abs(read - prev_val_x); - if (diff < prev_diff_x) { - prev_diff_x = diff; - *x = read; - } - prev_val_x = read; + for (i = 0; i < creads; i++) { + yvals[i] = titsc_readl(ts_dev, REG_FIFO0); + yvals[i] &= 0xfff; + } - } else if (channel == first_step + creads + 1) { - *z1 = read; + *z1 = titsc_readl(ts_dev, REG_FIFO0); + *z1 &= 0xfff; + *z2 = titsc_readl(ts_dev, REG_FIFO0); + *z2 &= 0xfff; - } else if (channel == first_step + creads + 2) { - *z2 = read; + for (i = 0; i < creads; i++) { + xvals[i] = titsc_readl(ts_dev, REG_FIFO0); + xvals[i] &= 0xfff; + } - } else if (channel > first_step) { - diff = abs(read - prev_val_y); - if (diff < prev_diff_y) { - prev_diff_y = diff; - *y = read; - } - prev_val_y = read; + /* + * If co-ordinates readouts is less than 4 then + * report the average. In case of 4 or more + * readouts, sort the co-ordinate samples, drop + * min and max values and report the average of + * remaining values. + */ + if (creads <= 3) { + for (i = 0; i < creads; i++) { + ysum += yvals[i]; + xsum += xvals[i]; } + ysum /= creads; + xsum /= creads; + } else { + sort(yvals, creads, sizeof(unsigned int), + titsc_cmp_coord, NULL); + sort(xvals, creads, sizeof(unsigned int), + titsc_cmp_coord, NULL); + for (i = 1; i < creads - 1; i++) { + ysum += yvals[i]; + xsum += xvals[i]; + } + ysum /= creads - 2; + xsum /= creads - 2; } + *y = ysum; + *x = xsum; } static irqreturn_t titsc_irq(int irq, void *dev) @@ -369,6 +375,11 @@ static int titsc_parse_dt(struct platform_device *pdev, if (err < 0) return err; + if (ts_dev->coordinate_readouts <= 0) { + dev_warn(&pdev->dev, "invalid co-ordinate readouts, resetting it to 5\n"); + ts_dev->coordinate_readouts = 5; + } + err = of_property_read_u32(node, "ti,charge-delay", &ts_dev->charge_delay); /*