From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751916Ab2HaCWm (ORCPT ); Thu, 30 Aug 2012 22:22:42 -0400 Received: from mga14.intel.com ([143.182.124.37]:41689 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751051Ab2HaCWk (ORCPT ); Thu, 30 Aug 2012 22:22:40 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.80,344,1344236400"; d="scan'208";a="139957180" Date: Fri, 31 Aug 2012 10:16:58 +0800 From: Feng Tang To: Alexander Stein Cc: Jean Delvare , , , "Ben Dooks (embedded platforms)" , Tomoya MORINAGA Subject: Re: i2c-eg20t: regression since i2c_add_numbered_adapter change Message-ID: <20120831101658.5ec81fa2@feng-i7> In-Reply-To: <6208908.ZjG7eB9lJn@ws-stein> References: <4401854.hVfHzgeqjT@ws-stein> <4378288.tkkLiQ5MQ7@ws-stein> <20120830171915.36b6d10b@feng-i7> <6208908.ZjG7eB9lJn@ws-stein> Organization: intel X-Mailer: Claws Mail 3.7.6 (GTK+ 2.22.0; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Alexander, On Thu, 30 Aug 2012 13:08:09 +0200 Alexander Stein wrote: > On Thursday 30 August 2012 17:19:15, Feng Tang wrote: > > > IMO the i2c_register_board_info only works in quite static setups. Especially with I2C-Busses attached to hotplugable PCI devices this way doesn't work reliable any more. > > > The device come and go dynamically so you can't assume fixed mapping. > > > > Can you specify the hotplugable? > > 1. A hotplugable i2c bus controller (say i2c_eg20t) with all fixed i2c > > devices connecting to it > > 2. i2c bus controller is fixed, while the i2c devices will be dynamically > > connected to it. > > 3. Both the bus controller and devices are dynamically hotplugged > > I had scenario 1 in mind, but with more than 1 bus controller (say 2x i2c_eg20t). How can you set a fixed numbering if there are more controllers, each with maybe more than 1 bus? > Anyway, how can you provide a static bus numbering if there are more than one driver or more than one device per driver if the devices are hotplugable? There is no problem for one pci driver to support multiple devices with same HW, if you check i2c-eg20t.c you can check the pch_pcidev_id[], there is a ML7213 platform which has 2 i2c controllers already. With current in tree driver, they will get fixed bus number 0 and 1. For the scenario 1, if you have really have another hotplugable pci eg20t controller, it surely will have its unique PCI id, and then we can use the "driver_data" of struct pci_device_id to point to a platform info structure like struct i2c_eg20t_platform_info { u16 bus_base_num; u16 total_hw_num; } And for EG20T compatible platform, I don't think it will have too many fancy hotplugable different type of i2c controller other than i2c_eg20t and i2c_sch. Thanks, Feng