Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965681AbcCPSZM (ORCPT ); Wed, 16 Mar 2016 14:25:12 -0400 Received: from mail-ob0-f179.google.com ([209.85.214.179]:35894 "EHLO mail-ob0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965617AbcCPSYz (ORCPT ); Wed, 16 Mar 2016 14:24:55 -0400 MIME-Version: 1.0 In-Reply-To: References: <1457372672-884-1-git-send-email-a.mathur@samsung.com> <56E17A73.8090901@bitmath.org> Date: Wed, 16 Mar 2016 23:54:54 +0530 Message-ID: Subject: Re: [PATCH] Input: Do not add SYN_REPORT in between a single packet data From: Aniroop Mathur To: Dmitry Torokhov , Henrik Rydberg Cc: Aniroop Mathur , "linux-input@vger.kernel.org" , lkml Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2438 Lines: 61 Hello Mr. Torokhov, Could you kindly help to update about this patch? Thank you, Aniroop Mathur On Fri, Mar 11, 2016 at 12:26 AM, Aniroop Mathur wrote: > Hi Henrik, > > On Thu, Mar 10, 2016 at 7:15 PM, Henrik Rydberg wrote: >> Hi Dmitry, >> >>>> diff --git a/drivers/input/input.c b/drivers/input/input.c >>>> index 8806059..262ef77 100644 >>>> --- a/drivers/input/input.c >>>> +++ b/drivers/input/input.c >>>> @@ -401,8 +401,7 @@ static void input_handle_event(struct input_dev *dev, >>>> if (dev->num_vals >= 2) >>>> input_pass_values(dev, dev->vals, dev->num_vals); >>>> dev->num_vals = 0; >>>> - } else if (dev->num_vals >= dev->max_vals - 2) { >>>> - dev->vals[dev->num_vals++] = input_value_sync; >>>> + } else if (dev->num_vals >= dev->max_vals - 1) { >>>> input_pass_values(dev, dev->vals, dev->num_vals); >>>> dev->num_vals = 0; >>>> } >>> >>> This makes sense to me. Henrik? >> >> I went through the commits that made these changes, and I cannot see any strong >> reason to keep it. However, this code path only triggers if no SYN events are >> seen, as in a driver that fails to emit them and consequently fills up the >> buffer. In other words, this change would only affect a device that is already, >> to some degree, broken. >> >> So, the question to Aniroop is: do you see this problem in practise, and in that >> case, for what driver? >> > > Nope. So far I have not dealt with any such driver. > I made this change because it is breaking protocol of SYN_REPORT event code. > > Further from the code, I could deduce that max_vals is just an estimation of > packet_size and it does not guarantee that packet_size is same as max_vals. > So real packet_size can be more than max_vals value and hence we could not > insert SYN_REPORT until packet ends really. > Further, if we consider that there exists a driver or will exist in future > which sets capability of x event code according to which max_value comes out to > y and the real packet size is z i.e. driver wants to send same event codes > again in the same packet, so input event reader would be expecting SYN_REPORT > after z events but due to current code SYN_REPORT will get inserted > automatically after y events, which is a wrong behaviour. > > Thanks, > Aniroop Mathur > >> Henrik >>