From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [PATCH v1] Input: elants_i2c: Add Elan touchscreen support Date: Thu, 20 Nov 2014 12:35:23 -0800 Message-ID: <20141120203523.GC14798@dtor-glaptop> References: <1388146515-19481-1-git-send-email-scott.liu@emc.com.tw> <20141120081113.GA37534@dtor-ws> <1416479490.28599.13.camel@linux-0dmf.site> <20141120174709.GA14798@dtor-glaptop> <1416515255.25223.1.camel@linux-0dmf.site> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-ie0-f177.google.com ([209.85.223.177]:40655 "EHLO mail-ie0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757783AbaKTUf0 (ORCPT ); Thu, 20 Nov 2014 15:35:26 -0500 Content-Disposition: inline In-Reply-To: <1416515255.25223.1.camel@linux-0dmf.site> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Oliver Neukum Cc: scott , linux-kernel@vger.kernel.org, linux-input@vger.kernel.org, Vincent Wang , Jeff Chuang , Benson Leung , Benjamin Tissoires , Henrik Rydberg , David Herrmann On Thu, Nov 20, 2014 at 09:27:35PM +0100, Oliver Neukum wrote: > On Thu, 2014-11-20 at 09:47 -0800, Dmitry Torokhov wrote: > > Hi Oliver, > > > > On Thu, Nov 20, 2014 at 11:31:30AM +0100, Oliver Neukum wrote: > > > > +static int elants_i2c_initialize(struct elants_data *ts) > > > > +{ > > > > + struct i2c_client *client = ts->client; > > > > + int error, retry_cnt; > > > > + const u8 hello_packet[] = { 0x55, 0x55, 0x55, 0x55 }; > > > > + const u8 recov_packet[] = { 0x55, 0x55, 0x80, 0x80 }; > > > > + u8 buf[HEADER_SIZE]; > > > > + > > > > > > Strictly speaking you should disable preemption here. > > > > Umm, why? > > You said the upper bound matters. So you need to protect yourself > against losing too much time by preemption. We are using i2c so we can't really disable preemption here... I think we have enough slack, although I would indeed lower the sleep time. I'll let Scott comment on that. Thanks. -- Dmitry