Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754121AbaG2PaT (ORCPT ); Tue, 29 Jul 2014 11:30:19 -0400 Received: from mail-lb0-f175.google.com ([209.85.217.175]:42134 "EHLO mail-lb0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753643AbaG2PaM (ORCPT ); Tue, 29 Jul 2014 11:30:12 -0400 MIME-Version: 1.0 In-Reply-To: <53D7AA72.6010309@mm-sol.com> References: <53D788A7.4020303@mm-sol.com> <3794875.CZFbAag5Sv@wuerfel> <53D7AA72.6010309@mm-sol.com> From: Rob Herring Date: Tue, 29 Jul 2014 10:29:50 -0500 Message-ID: Subject: Re: use IORESOURCE_REG resource type for non-translatable addresses in DT To: Stanimir Varbanov Cc: Arnd Bergmann , Grant Likely , Rob Herring , Lee Jones , "linux-arm-msm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" , linux-arm-kernel , Stephen Boyd , Mark Brown 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, Jul 29, 2014 at 9:06 AM, Stanimir Varbanov wrote: > Arnd, thanks for the comments. > > On 07/29/2014 03:00 PM, Arnd Bergmann wrote: >> On Tuesday 29 July 2014 14:42:31 Stanimir Varbanov wrote: >>> taddr = of_translate_address(dev, addrp); >>> - if (taddr == OF_BAD_ADDR) >>> - return -EINVAL; >>> + /* >>> + * if the address is non-translatable to cpu physical address >>> + * fallback to a IORESOURCE_REG resource. >>> + */ >>> + if (taddr == OF_BAD_ADDR) { >>> + memset(r, 0, sizeof(*r)); >>> + taddr = of_read_number(addrp, 1); >>> + if (taddr == OF_BAD_ADDR) >>> + return -EINVAL; >>> + r->start = taddr; >>> + r->end = taddr + size - 1; >>> + r->flags = IORESOURCE_REG; >>> + r->name = name ? name : dev->full_name; >>> + return 0; >>> + } >>> + >> >> I don't think that everything returning OF_BAD_ADDR makes sense >> to turn into IORESOURCE_REG. It could be an e.g. invalid DT >> representation, a node with #size-cells=<0>, or it could be >> something that gets translated one or more nodes up in the >> tree before it reaches a bus without a ranges property. >> >> Also, you should not rely on #address-cells being hardcoded >> to <1> above. >> > > This was just an example. Of course it has many issues and probaly it is > wrong:) The main goal was to understand does IORESOURCE_REG resource > type and parsing the *reg* properties for non-translatable addresses are > feasible. And also does it acceptable by community and OF platform > maintainers. I guess the question I have is what is the advantage of making this a resource? You can't really pass it to other functions. We're moving in the opposite direction for IRQs as now platform_get_irq translates the IRQ directly rather than using the resource (but the resource is still there just to avoid potentially breaking things for now). >> How about modifying of_get_address() rather than >> __of_address_to_resource() instead? You could introduce >> a new of_bus entry for each bus you expect to return >> an IORESOURCE_REG, or you could change of_bus_default_get_flags >> to return IORESOURCE_REG if the parent node has no ranges property >> and is not the root node. > > IMO the clearer solution is to introduce a new of_bus bus. In that case > one possible problem will be how to distinguish the non-translatable and > the other buses. Also the *device_type* property is deprecated for non > PCI devices. You would have to look for the presence or absence of ranges property. Rob -- 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/