Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262609AbVBBVB4 (ORCPT ); Wed, 2 Feb 2005 16:01:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262593AbVBBVBu (ORCPT ); Wed, 2 Feb 2005 16:01:50 -0500 Received: from av7-2-sn4.m-sp.skanova.net ([81.228.10.109]:40894 "EHLO av7-2-sn4.m-sp.skanova.net") by vger.kernel.org with ESMTP id S262833AbVBBU5q (ORCPT ); Wed, 2 Feb 2005 15:57:46 -0500 To: Pete Zaitcev Cc: vojtech@suse.cz, linux-kernel@vger.kernel.org, Subject: Re: Touchpad problems with 2.6.11-rc2 References: <20050123190109.3d082021@localhost.localdomain> <20050201234148.4d5eac55@localhost.localdomain> From: Peter Osterlund Date: 02 Feb 2005 21:57:39 +0100 In-Reply-To: <20050201234148.4d5eac55@localhost.localdomain> Message-ID: User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3615 Lines: 89 Pete Zaitcev writes: > On 30 Jan 2005 12:10:34 +0100, Peter Osterlund wrote: > > > > - Slow motion of finger produces no motion, then a jump. So, it's very hard to > > > target smaller UI elements and some web links. > > > > I see this too when I don't use the X touchpad driver. With the X > > driver there is no problem. I think the problem is that mousedev.c in > > the kernel has to use integer arithmetic, so probably small movements > > are rounded off to 0. I'll try to come up with a fix for this. > > Thanks for the hint. I tried various schemes and mathematical transformations > and found one which gives unquestionably the best result, with smoothest, most > precise and comfortable pointer movement: Please try this patch instead. It works well with my alps touchpad. (I don't have a synaptics touchpad.) It does the following: * Compensates for the lack of floating point arithmetic by keeping track of remainders from the integer divisions. * Removes the xres/yres scaling so that you get the same speed in the X and Y directions even if your screen is not square. * Sets scale factors so that the speed for synaptics and alps should be equal to each other and equal to the synaptics speed from 2.6.10. Signed-off-by: Peter Osterlund --- linux-petero/drivers/input/mousedev.c | 26 +++++++++++++++++--------- 1 files changed, 17 insertions(+), 9 deletions(-) diff -puN drivers/input/mousedev.c~mousedev-roundoff drivers/input/mousedev.c --- linux/drivers/input/mousedev.c~mousedev-roundoff 2005-02-02 20:54:23.000000000 +0100 +++ linux-petero/drivers/input/mousedev.c 2005-02-02 21:42:39.000000000 +0100 @@ -71,6 +71,7 @@ struct mousedev { struct mousedev_hw_data packet; unsigned int pkt_count; int old_x[4], old_y[4]; + int frac_dx, frac_dy; unsigned long touch; }; @@ -117,24 +118,31 @@ static struct mousedev mousedev_mix; static void mousedev_touchpad_event(struct input_dev *dev, struct mousedev *mousedev, unsigned int code, int value) { - int size; + int size, tmp; +#define FRACTION_DENOM 100 if (mousedev->touch) { + size = dev->absmax[ABS_X] - dev->absmin[ABS_X]; + if (size == 0) size = xres; switch (code) { case ABS_X: - size = dev->absmax[ABS_X] - dev->absmin[ABS_X]; - if (size == 0) size = xres; fx(0) = value; - if (mousedev->pkt_count >= 2) - mousedev->packet.dx = ((fx(0) - fx(1)) / 2 + (fx(1) - fx(2)) / 2) * xres / (size * 2); + if (mousedev->pkt_count >= 2) { + tmp = ((fx(0) - fx(2)) * (250 * FRACTION_DENOM)) / size; + tmp += mousedev->frac_dx; + mousedev->packet.dx = tmp / FRACTION_DENOM; + mousedev->frac_dx = tmp - mousedev->packet.dx * FRACTION_DENOM; + } break; case ABS_Y: - size = dev->absmax[ABS_Y] - dev->absmin[ABS_Y]; - if (size == 0) size = yres; fy(0) = value; - if (mousedev->pkt_count >= 2) - mousedev->packet.dy = -((fy(0) - fy(1)) / 2 + (fy(1) - fy(2)) / 2) * yres / (size * 2); + if (mousedev->pkt_count >= 2) { + tmp = -((fy(0) - fy(2)) * (250 * FRACTION_DENOM)) / size; + tmp += mousedev->frac_dy; + mousedev->packet.dy = tmp / FRACTION_DENOM; + mousedev->frac_dy = tmp - mousedev->packet.dy * FRACTION_DENOM; + } break; } } _ -- Peter Osterlund - petero2@telia.com http://web.telia.com/~u89404340 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/