From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755265Ab1HRIEd (ORCPT ); Thu, 18 Aug 2011 04:04:33 -0400 Received: from emcscan.emc.com.tw ([192.72.220.5]:19541 "EHLO emcscan.emc.com.tw" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752123Ab1HRIE3 (ORCPT ); Thu, 18 Aug 2011 04:04:29 -0400 From: JJ Ding To: Dmitry Torokhov Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Seth Forshee , Aaron Huang , Tom Lin , Eric Piel , Daniel Kurtz , Chase Douglas , Henrik Rydberg , Alessandro Rubini Subject: Re: [PATCH 3/6] Input: elantech - packet checking for v2 hardware In-Reply-To: <20110818075226.GF10093@core.coreip.homeip.net> References: <1313632629-23603-1-git-send-email-jj_ding@emc.com.tw> <1313632629-23603-4-git-send-email-jj_ding@emc.com.tw> <20110818063818.GC10093@core.coreip.homeip.net> <87wreb2n1s.fsf@emc.com.tw> <20110818075226.GF10093@core.coreip.homeip.net> User-Agent: Notmuch/0.5 (http://notmuchmail.org) Emacs/23.2.1 (i686-pc-linux-gnu) Date: Thu, 18 Aug 2011 16:06:44 +0800 Message-ID: <87r54j2lez.fsf@emc.com.tw> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Dmitry, On Thu, 18 Aug 2011 00:52:26 -0700, Dmitry Torokhov wrote: > On Thu, Aug 18, 2011 at 03:31:27PM +0800, JJ Ding wrote: > > Hi Dmitry, > > > > On Wed, 17 Aug 2011 23:38:18 -0700, Dmitry Torokhov wrote: > > > On Thu, Aug 18, 2011 at 09:57:06AM +0800, JJ Ding wrote: > > > > For v2 hardware, there is no real parity check, but we can still check > > > > some constant bits for data integrity. > > > > > > > > Signed-off-by: JJ Ding > > > > --- > > > > drivers/input/mouse/elantech.c | 26 +++++++++++++++++++++++--- > > > > 1 files changed, 23 insertions(+), 3 deletions(-) > > > > > > > > diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c > > > > index cf41f23..032181c 100644 > > > > --- a/drivers/input/mouse/elantech.c > > > > +++ b/drivers/input/mouse/elantech.c > > > > @@ -376,6 +376,25 @@ static int elantech_check_parity_v1(struct psmouse *psmouse) > > > > etd->parity[packet[3]] == p3; > > > > } > > > > > > > > +static int packet_simple_check_v2(struct psmouse *psmouse) > > > > +{ > > > > + struct elantech_data *etd = psmouse->private; > > > > + unsigned char *packet = psmouse->packet; > > > > + > > > > + if (etd->reports_pressure) > > > > + return (packet[0] & 0x0c) == 0x04 && > > > > + (packet[3] & 0x0f) == 0x02; > > this is for newer v2 hardware > > > > > > + > > > > + if ((packet[0] & 0xc0) == 0x80) > > > > + return (packet[0] & 0x0c) == 0x0c && > > > > + (packet[3] & 0x0e) == 0x08; > > this is for older v2, two finger touch > > > > > > + > > > > + return (packet[0] & 0x3c) == 0x3c && > > > > + (packet[1] & 0xf0) == 0x00 && > > > > + (packet[3] & 0x3e) == 0x38 && > > > > + (packet[4] & 0xf0) == 0x00; > > this is for older v2, 1/3 finger touch > > > > > > > > Can we please spell out the assumptions under which we decide that > > > packet is invalid? > > > > > > Thanks. > > > > > > -- > > > Dmitry > > V2 hardware has two flavors. Older ones that do not report pressure, > > and newer ones that reports pressure and width. > > > > With newer ones, all packets (1, 2, 3 finger touch) have the same > > constant bits. > > > > With older ones, 1/3 finger touch packets and 2 finger touch packets have > > different constant bits. > > > > With all three cases, if the constant bits are not exactly what I > > expected, I consider them invalid. > > > > Dmitry, how do you want me to improve this? not enough comments? > > Right, if you could put the above into comments right in the > packet_simple_check_v2() that woudl be great. > > Thanks. No problem. I will do that. > -- > Dmitry > -- > To unsubscribe from this list: send the line "unsubscribe linux-input" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html