Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932518Ab3FFLA6 (ORCPT ); Thu, 6 Jun 2013 07:00:58 -0400 Received: from kdh-gw.itdev.co.uk ([89.21.227.133]:8616 "EHLO hermes.kdh.itdev.co.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751521Ab3FFLA5 (ORCPT ); Thu, 6 Jun 2013 07:00:57 -0400 Message-ID: <51B06BE6.80909@itdev.co.uk> Date: Thu, 06 Jun 2013 12:00:54 +0100 From: Nick Dyer User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130510 Thunderbird/17.0.6 MIME-Version: 1.0 To: Mark Brown CC: Dmitry Torokhov , Daniel Kurtz , Henrik Rydberg , Joonyoung Shim , Alan.Bowens@atmel.com, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, pmeerw@pmeerw.net, bleung@chromium.org, olofj@chromium.org Subject: Re: [PATCH 10/53] Input: atmel_mxt_ts - Add memory access interface via sysfs References: <1370453866-16534-1-git-send-email-nick.dyer@itdev.co.uk> <7380889.l4hHqCT0mm@dtor-d630.eng.vmware.com> <51AF8730.4010507@itdev.co.uk> <1717403.GgHsbyUkDZ@dtor-d630.eng.vmware.com> <51AFA02B.3000604@itdev.co.uk> <20130605210715.GA16013@core.coreip.homeip.net> <20130606094822.GB1883@sirena.org.uk> <51B06732.2050701@itdev.co.uk> <20130606104651.GS31367@sirena.org.uk> In-Reply-To: <20130606104651.GS31367@sirena.org.uk> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1463 Lines: 31 Mark Brown wrote: > On Thu, Jun 06, 2013 at 11:40:50AM +0100, Nick Dyer wrote: > >> I am more worried about the address pointer handling and the I2C retries. > > The retries can just be done further up the stack? All regmap is doing > with I/O errors is punting them straight back up to the caller so the > caller can retry just as well using regmap as it can using the raw I/O > protocol. It would have to be put into users of the debugfs interface as well. There's quite tight timing required to make it work properly (see patch [40/53]). > Without seeing the address thing it's hard to comment. Patch [36/53]. If the T5 message processor is from address 100-110, you can do a read of 50 bytes starting at address 100, and it will return 10 messages, but anything in regmap that tries to do bounds checking would get confused, I think. Also, we would like to implement address pointer caching. maXTouch allows us to skip the address part of the i2c transaction if the address pointer in the chip hasn't changed. This speeds up interrupt handler slightly. But it requires extra housekeeping at a low level to remember what the address pointer was on the previous transaction to know whether to send it or not. -- 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/