From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755263AbcGESHp (ORCPT ); Tue, 5 Jul 2016 14:07:45 -0400 Received: from mail-wm0-f49.google.com ([74.125.82.49]:37149 "EHLO mail-wm0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755149AbcGESHk convert rfc822-to-8bit (ORCPT ); Tue, 5 Jul 2016 14:07:40 -0400 Subject: Re: portable device tree connector -- problem statement Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Content-Type: text/plain; charset=windows-1252 From: Pantelis Antoniou In-Reply-To: <577BC30C.10105@gmail.com> Date: Tue, 5 Jul 2016 21:07:34 +0300 Cc: Mark Brown , Rob Herring , David Gibson , stephen.boyd@linaro.org, Grant Likely , Mark Rutland , Matt Porter , Koen Kooi , Guenter Roeck , marex@denx.de, Wolfram Sang , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org Content-Transfer-Encoding: 8BIT Message-Id: References: <577ACE0D.9050700@gmail.com> <20160705083152.GM6247@sirena.org.uk> <577BC30C.10105@gmail.com> To: Frank Rowand X-Mailer: Apple Mail (2.3124) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Frank, > On Jul 5, 2016, at 17:24 , Frank Rowand wrote: > > On 07/05/16 01:31, Mark Brown wrote: >> On Mon, Jul 04, 2016 at 01:58:53PM -0700, Frank Rowand wrote: >> >>> On the other hand, I have no previous detailed knowledge of the beagle >>> family. >> >> This is in no way specific to the BeagleBones, there's plenty of other >> boards out there with similar setups like the Raspberry Pi and its >> derivatives. > > Yes, absolutely. I'm just picking on the beaglebones because that is > what Pantelis has recently used for examples. (He has mentioned other > connector types and expansion boards in his presentations.) > > And we need to think beyond beaglebone, pi, arduino, and grove > type of connectors. > > Some other connectors that are obvious are pci and possibly usb. > Yes, in fact a growing number of platforms come with discoverable PCI/USB boards which provide the busses and interfaces that non-discoverable boards are plugged in. Think an i2c-bus on pci-e boards on which a number of I2C peripherals are located. The Vendor/Product IDs are the same for all these expansions boards since the h/w designers do not want to spend money on even a dip-switch or EEPROM for the IDs. > >>> - for bones with the same pinout: >>> - the pins are routed to different function blocks on the >>> SOC because different bones may have different SOCs? >>> - the different functional blocks are compatible or not? >> >> This is the general case, there will be a substantial level of >> compatibility between different base boards by virtue of the pinouts >> being the same but obviously there will be some variation in the >> specifics (and even where that exists it may not be enough to be visible >> at the DT level for the most part). That said there will doubtless be >> some plug in modules that want to rely on the specifics of a given base >> board rather than remain compatible with general users of the interface. >> > Regards — Pantelis