Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756941Ab2HTPKB (ORCPT ); Mon, 20 Aug 2012 11:10:01 -0400 Received: from mail-qa0-f53.google.com ([209.85.216.53]:58923 "EHLO mail-qa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756808Ab2HTPJ5 (ORCPT ); Mon, 20 Aug 2012 11:09:57 -0400 MIME-Version: 1.0 In-Reply-To: <50324835.6030806@gmail.com> References: <1345462769-17386-1-git-send-email-aletes.xgr@gmail.com> <50324835.6030806@gmail.com> Date: Mon, 20 Aug 2012 17:09:57 +0200 Message-ID: Subject: Re: [PATCH RESEND v4] spi/pl022: add devicetree support From: Linus Walleij To: Rob Herring Cc: Alexandre Pereira da Silva , Roland Stigge , Grant Likely , Rob Landley , devicetree-discuss@lists.ozlabs.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, spi-devel-general@lists.sourceforge.net, "Mark Brown (broonie@opensource.wolfsonmicro.com)" , Viresh Kumar , sachin.verma@st.co Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2183 Lines: 55 On Mon, Aug 20, 2012 at 4:22 PM, Rob Herring wrote: > On 08/20/2012 06:39 AM, Alexandre Pereira da Silva wrote: >> +- pl022,hierarchy : master or slave interface > > Is attaching a master and using the pl022 as a slave really a supported > use case? No not currently. People doing this crazy stuff need to have the kernel with the hard real-time patches and lightening response first. But it's in the platform data because it's a feature supported by the hardware. > The DT spi bindings are really designed for a master node with > N slave nodes. So there is more general question of how to describe a > spi controller as a slave. It's not really one I care to answer as the > Linux spi framework isn't designed to act as a slave. Currently the code should hardwire this to master and not define a binding for it I think. >> +- pl022,slave-tx-disable : disconnect tx line in slave mode Applies also to this, then. >> +- pl022,com-mode : polling, interrupt or dma >> +- pl022,rx-level-trig : Rx FIFO watermark level >> +- pl022,tx-level-trig : Tx FIFO watermark level >> +- pl022,ctrl-len : Microwire interface: Control length >> +- pl022,wait-state : Microwire interface: Wait state >> +- pl022,duplex : Microwire interface: Full/Half duplex > > Most of these properties aren't used anywhere in the kernel other than > u300 and I'm not sure what to purpose of dummy_chip_info is. It is used for loopback-testing of the PL022. They're probably not necessary there either. > Perhaps > Linus has some input? I think either they can be decided by the spi > controller (com-mode, fifo watermark) or should be standard properties > (microwire settings). I would argue they should be removed if the spi > framework doesn't have support in a standard way. Uncertain about this, others would need to comment. At some point there has been a chip needing these to be set to some magic values. Yours, Linus Walleij -- 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/