From patchwork Tue Nov 11 08:34:04 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vignesh Raghavendra X-Patchwork-Id: 5271621 Return-Path: X-Original-To: patchwork-linux-arm@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 EA968C11AC for ; Tue, 11 Nov 2014 08:39:37 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id F3CE920103 for ; Tue, 11 Nov 2014 08:39:36 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 039092010E for ; Tue, 11 Nov 2014 08:39:36 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1Xo6xN-000328-PM; Tue, 11 Nov 2014 08:37:45 +0000 Received: from arroyo.ext.ti.com ([192.94.94.40]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Xo6wu-0002bQ-TA for linux-arm-kernel@lists.infradead.org; Tue, 11 Nov 2014 08:37:17 +0000 Received: from dflxv15.itg.ti.com ([128.247.5.124]) by arroyo.ext.ti.com (8.13.7/8.13.7) with ESMTP id sAB8aBmg023952; Tue, 11 Nov 2014 02:36:11 -0600 Received: from DFLE72.ent.ti.com (dfle72.ent.ti.com [128.247.5.109]) by dflxv15.itg.ti.com (8.14.3/8.13.8) with ESMTP id sAB8aBWl022975; Tue, 11 Nov 2014 02:36:11 -0600 Received: from dlep32.itg.ti.com (157.170.170.100) by DFLE72.ent.ti.com (128.247.5.109) with Microsoft SMTP Server id 14.3.174.1; Tue, 11 Nov 2014 02:36:11 -0600 Received: from uda0132425.apr.dhcp.ti.com (ileax41-snat.itg.ti.com [10.172.224.153]) by dlep32.itg.ti.com (8.14.3/8.13.8) with ESMTP id sAB8ZDe7024824; Tue, 11 Nov 2014 02:36:03 -0600 From: Vignesh R To: Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Benoit Cousson , Tony Lindgren , Russell King , Jonathan Cameron , Hartmut Knaack , , Dmitry Torokhov , Lee Jones , Sebastian Andrzej Siewior Subject: [PATCH v3 6/6] input: touchscreen: ti_am335x_tsc: Replace delta filtering with median filtering Date: Tue, 11 Nov 2014 14:04:04 +0530 Message-ID: <1415694844-11230-7-git-send-email-vigneshr@ti.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1415694844-11230-1-git-send-email-vigneshr@ti.com> References: <1415694844-11230-1-git-send-email-vigneshr@ti.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20141111_003717_085183_217286FE X-CRM114-Status: GOOD ( 19.46 ) X-Spam-Score: -5.6 (-----) Cc: devicetree@vger.kernel.org, linux-iio@vger.kernel.org, Lars-Peter Clausen , Brad Griffis , Jan Kardell , Vignesh R , linux-kernel@vger.kernel.org, Felipe Balbi , Paul Gortmaker , Peter Meerwald , linux-input@vger.kernel.org, Sanjeev Sharma , linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Samuel Ortiz X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-3.1 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_LOW, 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 20ce76b1b6e7..e1df470946e6 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) @@ -362,6 +368,11 @@ 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); if (err < 0)