From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752925AbcHOMDE (ORCPT ); Mon, 15 Aug 2016 08:03:04 -0400 Received: from mga03.intel.com ([134.134.136.65]:13590 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752684AbcHOMDD (ORCPT ); Mon, 15 Aug 2016 08:03:03 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.28,525,1464678000"; d="scan'208";a="155904151" Date: Mon, 15 Aug 2016 15:02:58 +0300 From: Heikki Krogerus To: Tal Shorer Cc: gregkh@linuxfoundation.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, balbi@kernel.org Subject: Re: [PATCH v2 00/10] usb: ulpi: remove "dev" field from struct ulpi_ops Message-ID: <20160815120258.GA11370@kuha.fi.intel.com> References: <1470075358-19792-1-git-send-email-tal.shorer@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1470075358-19792-1-git-send-email-tal.shorer@gmail.com> User-Agent: Mutt/1.6.2 (2016-07-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Please forgive me for taking so long to reply. I just returned from paternal leave. On Mon, Aug 01, 2016 at 09:15:48PM +0300, Tal Shorer wrote: > struct ulpi_ops is defined as follows: > > struct ulpi_ops { > struct device *dev; > int (*read)(struct ulpi_ops *ops, u8 addr); > int (*write)(struct ulpi_ops *ops, u8 addr, u8 val); > }; > > Upon calling ulpi_register_interface(), the struct device argument is > put inside the struct ulpi_ops argument's dev field. Later, when > calling the actual read()/write() operations, the struct ulpi_ops is > passed to them and they use the stored device to access whatever > private data they need. > > This means that if one wishes to reuse the same oprations for multiple > interfaces (e.g if we have multiple instances of the same controller), > any but the last interface registered will not operate properly (and > the one that does work will be at the mercy of the others to not mess > it up). > > I understand that barely any driver uses this bus right now, but I > suppose it's there to be used at some point. We might as well fix the > design here before we hit this bug. > > This series fixes this by passing the given struct device directly to > the operation functions via ulpi->dev.parent in ulpi_read() and > ulpi_write(). It also changes the operations struct to be constant > since now nobody has a reason to modify it. If there are multiple instances of the same controller, the controller driver just needs to provide a separate ops for every one of them. This isn't really a problem as you describe it. But I'm not against API improvements even if they don't fix anything. I'll test these tomorrow. Thanks, -- heikki