From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753044AbdF2M72 (ORCPT ); Thu, 29 Jun 2017 08:59:28 -0400 Received: from mx08-00178001.pphosted.com ([91.207.212.93]:46389 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752740AbdF2M7T (ORCPT ); Thu, 29 Jun 2017 08:59:19 -0400 Subject: Re: [PATCHv2 9/9] spi: spidev: add Aardvark to device tree compatibility list To: Mark Brown CC: Rob Herring , Mark Rutland , Maxime Coquelin , Alexandre TORGUE , "linux-spi@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" References: <1498578321-13980-1-git-send-email-amelie.delaunay@st.com> <1498578321-13980-10-git-send-email-amelie.delaunay@st.com> <20170628185445.fsnqs2tlqqeqzl57@sirena.org.uk> From: Amelie DELAUNAY Message-ID: <67764839-889b-e398-16eb-de583d82cbf3@st.com> Date: Thu, 29 Jun 2017 14:58:43 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: <20170628185445.fsnqs2tlqqeqzl57@sirena.org.uk> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.75.127.46] X-ClientProxiedBy: SFHDAG8NODE2.st.com (10.75.127.23) To SFHDAG3NODE2.st.com (10.75.127.8) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-06-29_09:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/28/2017 08:54 PM, Mark Brown wrote: > On Tue, Jun 27, 2017 at 05:45:21PM +0200, Amelie Delaunay wrote: >> This patch adds an entry for the TotalPhase Aardvark SPI Host Adapter, >> which can operate as an SPI Slave. > > What does this device actually do and why is spidev a sensible fit for > it? > This device is actually a debugging tool [1] which can work on SPI bus (and also I2C). Connected via USB on a PC, it can either acts as an SPI master or SPI slave and it can transmit/receive serial data using SPI protocol. Polarity, Phase, Bit Order, Frequency can be configured. So this tool is really useful during SPI driver development to troubleshoot. And that's why spidev driver totally fit for it when used as an SPI slave, for the reason described in spidev Documentation: "Developing simple protocols used to talk to" Aardvark "acting as SPI slaves, which you may need to change quite often". [1] https://www.totalphase.com/products/aardvark-i2cspi/