Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754596Ab2KIQgN (ORCPT ); Fri, 9 Nov 2012 11:36:13 -0500 Received: from mail-wi0-f178.google.com ([209.85.212.178]:36633 "EHLO mail-wi0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754503Ab2KIQgJ (ORCPT ); Fri, 9 Nov 2012 11:36:09 -0500 MIME-Version: 1.0 In-Reply-To: References: <1351928793-14375-1-git-send-email-mika.westerberg@linux.intel.com> <3455360.Z6cZSC3BtR@vostro.rjw.lan> <1523215.Pon1eKPQDb@vostro.rjw.lan> <20121107095608.GX24532@intel.com> <20121108200445.GC16012@intel.com> From: Bjorn Helgaas Date: Fri, 9 Nov 2012 09:35:46 -0700 Message-ID: Subject: Re: [PATCH 2/3] spi / ACPI: add ACPI enumeration support To: Grant Likely Cc: Mika Westerberg , "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, lenb@kernel.org, rafael.j.wysocki@intel.com, broonie@opensource.wolfsonmicro.com, linus.walleij@linaro.org, khali@linux-fr.org, ben-linux@fluff.org, w.sang@pengutronix.de, mathias.nyman@linux.intel.com, linux-acpi@vger.kernel.org, Greg Kroah-Hartman , "H. Peter Anvin" , Tony Luck Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2734 Lines: 54 On Fri, Nov 9, 2012 at 8:45 AM, Grant Likely wrote: > On Fri, Nov 9, 2012 at 3:11 PM, Bjorn Helgaas wrote: >> [+cc Greg, Peter, Tony since they acked the original patch [1]] >> >> On Thu, Nov 8, 2012 at 1:04 PM, Mika Westerberg >> wrote: >>> On Thu, Nov 08, 2012 at 12:32:25PM -0700, Bjorn Helgaas wrote: >>>> Struct device_driver is a generic structure, so it seems strange to >>>> have to include non-generic things like of_device_id and now >>>> acpi_match_table there. >>> >>> Yes, but in a sense the DT and ACPI are "generic". So that they are used to >>> describe the configuration of a machine. >> >> What I meant by "generic" was "useful across all architectures." The >> new acpi_match_table and acpi_handle fields [1] are not generic in >> that sense because they're present on all architectures but used only >> on x86 and ia64. The existing of_match_table and of_node are >> similarly unused on many architectures. This doesn't seem like a >> scalable strategy to me. Are we going to add a pnpbios_node for x86 >> PNPBIOS machines without ACPI, a pdc_hpa for parisc machines with PDC, >> etc.? >> >> [1] https://patchwork.kernel.org/patch/1677221/ > > Ultimately yes, I think that is what we want to do, Just to be clear, you think we *should* add things like pnpbios_node, pdc_hpa, etc., to struct device, one field for every scheme of telling the OS about non-enumerable devices, where only one of the N fields is used on any given machine? That seems surprising to me, but maybe I just need to be educated :) > but there is first > the non-trivial problem to solve of figuring out how ACPI/DT/whatever > data maps into what the driver expects. For example, say a device uses > two GPIOs (A & B) and we have a generic get_gpio(int index) function > that works for both ACPI and DT. But what if the ACPI binding has the > gpios in the order A,B and DT orders them B,A? I do want to coordinate > between the DT and ACPI camps to avoid those situations as much as > possible, but they will happen. When they do the driver will still > need firmware specific data. It doesn't make any sense to put that > stuff outside the driver because only that specific driver needs the > extra information. Sure. This seems like just a special case of "drivers need a way to access the underlying ACPI/DT/whatever-specific functionality," e.g., gpio = get_gpio(dev, dev_is_acpi(dev) ? 1 : 0); -- 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/