Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757496AbaDHQyZ (ORCPT ); Tue, 8 Apr 2014 12:54:25 -0400 Received: from mail-ie0-f178.google.com ([209.85.223.178]:37767 "EHLO mail-ie0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756079AbaDHQyW (ORCPT ); Tue, 8 Apr 2014 12:54:22 -0400 MIME-Version: 1.0 In-Reply-To: <4778371.oH3kIlbD0f@wuerfel> References: <1394811272-1547-1-git-send-email-Liviu.Dudau@arm.com> <20140408095038.GT17163@e106497-lin.cambridge.arm.com> <4778371.oH3kIlbD0f@wuerfel> From: Bjorn Helgaas Date: Tue, 8 Apr 2014 10:54:01 -0600 Message-ID: Subject: Re: [PATCH v7 1/6] pci: Introduce pci_register_io_range() helper function. To: Arnd Bergmann Cc: Liviu Dudau , linux-pci , Catalin Marinas , Will Deacon , Benjamin Herrenschmidt , linaro-kernel , LKML , "devicetree@vger.kernel.org" , LAKML , Tanmay Inamdar , Grant Likely Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 8, 2014 at 4:22 AM, Arnd Bergmann wrote: > On Tuesday 08 April 2014 10:50:39 Liviu Dudau wrote: >> On Mon, Apr 07, 2014 at 06:58:24PM +0100, Bjorn Helgaas wrote: >> > On Mon, Apr 7, 2014 at 5:36 AM, Arnd Bergmann wrote: >> > >> > > I think migrating other architectures to use the same code should be >> > > a separate effort from adding a generic implementation that can be >> > > used by arm64. It's probably a good idea to have patches to convert >> > > arm32 and/or microblaze. >> > >> > Let me reiterate that I am 100% in favor of replacing arch-specific >> > code with more generic implementations. >> > >> > However, I am not 100% in favor of doing it as separate efforts >> > (although maybe I could be convinced). The reasons I hesitate are >> > that (1) if only one architecture uses a new "generic" implementation, >> > we really don't know whether it is generic enough, (2) until I see the >> > patches to convert other architectures, I have to assume that I'm the >> > one who will write them, and (3) as soon as we add the code to >> > drivers/pci, it becomes partly my headache to maintain it, even if >> > only one arch benefits from it. > > Fair enough. > > My approach to the asm-generic infrastruction has mostly been to ensure > that whoever adds a new architecture has to make things easier for the > next person. That's a good rule. But if we add a generic implementation used only by one architecture, the overall complexity has increased (we added new unshared code), so the next person has to look at N+1 existing implementations. If we even convert one existing arch, that seems like an improvement: we have N implementations with one being used by at least two arches. Bjorn -- 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/