From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux Subject: Re: [PATCH] ads7846: allocate separate cache lines for tx and rx data Date: Thu, 16 Jul 2009 08:22:26 +0100 Message-ID: <20090716072226.GA8113@n2100.arm.linux.org.uk> References: <200907151106.47917.david-b@pacbell.net> <20090715093313.GA2897@mail.gnudd.com> <20090715193326.GA13306@mail.gnudd.com> <20090716071529.GA28840@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from caramon.arm.linux.org.uk ([78.32.30.218]:52984 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751586AbZGPHWn (ORCPT ); Thu, 16 Jul 2009 03:22:43 -0400 Content-Disposition: inline In-Reply-To: <20090716071529.GA28840@n2100.arm.linux.org.uk> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Alessandro Rubini Cc: david-b@pacbell.net, linux-input@vger.kernel.org, linux-arm-kernel@lists.arm.linux.org.uk On Thu, Jul 16, 2009 at 08:15:29AM +0100, Russell King - ARM Linux wrote: > On Wed, Jul 15, 2009 at 09:33:26PM +0200, Alessandro Rubini wrote: > > >> The issue was discussed with Russell King on linux-arm-kernel. > > > > > > Gee, but not with the author of that driver or the maintainer of > > > the SPI framework. Who could have pointed out instantly where > > > the true bug resides. > > > > So, where is it? I don't get it I'm sorry. > > Clearly David has no knowledge of DMA cache line handing and has not > read the DMA API document. I really suggest that you ignore him until > he gets a fucking clue. ... and until that happens, I suggest you remove the ADS7846 chip from your hardware; as that DMA stuff in the driver currently stands, it can NEVER work on ARM or any other DMA cache incoherent CPU which uses DMA for SPI transfers.