From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alessandro Rubini Subject: Re: [PATCH] ads7846: allocate separate cache lines for tx and rx data Date: Thu, 16 Jul 2009 10:15:27 +0200 Message-ID: <20090716081527.GA29374@mail.gnudd.com> References: <200907160051.04506.david-b@pacbell.net> <200907151106.47917.david-b@pacbell.net> <20090715093313.GA2897@mail.gnudd.com> <20090715193326.GA13306@mail.gnudd.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Return-path: Received: from mail2.gnudd.com ([213.203.150.91]:63037 "EHLO mail.gnudd.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752916AbZGPIPv (ORCPT ); Thu, 16 Jul 2009 04:15:51 -0400 Content-Disposition: inline In-Reply-To: <200907160051.04506.david-b@pacbell.net> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: dbrownell@users.sourceforge.net Cc: linux-input@vger.kernel.org, linux@arm.linux.org.uk, linux-arm-kernel@lists.arm.linux.org.uk > If you're referring to the way the spi_message and spi_transfer > structs sit in the same cache lines as the data buffers, that's > something that should get fixed. Yes, that's what my patch did. The "strange" part is using a single malloc instead of three (re-reading your message, the full-duplex isn't involved here, so I'm not sure tx and rx data can safely be merged in a cache line). > It seems that e8f462d202026d8e99f553ed5a09422321226ac9 wasn't a > complete fix ... this explains why the touchscreen behaves but > not the ADC inputs (as you noted). Yes, basically I did the same split of data from control. > Note that this issue is unrelated to full duplex DMA support. Yes, that's right. But full duplex is not involved here, it's just 2 or 3 rounds of "one byte tx then two bytes rx". /alessandro