Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753591AbbGAG4J (ORCPT ); Wed, 1 Jul 2015 02:56:09 -0400 Received: from mail-wg0-f41.google.com ([74.125.82.41]:33142 "EHLO mail-wg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751125AbbGAGz6 (ORCPT ); Wed, 1 Jul 2015 02:55:58 -0400 MIME-Version: 1.0 In-Reply-To: <20150701062352.GA3739@lst.de> References: <20150622081028.35954.89885.stgit@dwillia2-desk3.jf.intel.com> <20150622082427.35954.73529.stgit@dwillia2-desk3.jf.intel.com> <20150622161002.GB8240@lst.de> <20150701062352.GA3739@lst.de> Date: Wed, 1 Jul 2015 08:55:57 +0200 X-Google-Sender-Auth: L1cPDr63NbXjHYZPCR1zcVn8FsQ Message-ID: Subject: Re: [PATCH v5 2/6] arch: unify ioremap prototypes and macro aliases From: Geert Uytterhoeven To: Christoph Hellwig Cc: Dan Williams , Arnd Bergmann , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Thomas Gleixner , Ross Zwisler , Andrew Morton , Juergen Gross , X86 ML , "Kani, Toshimitsu" , "linux-nvdimm@lists.01.org" , Benjamin Herrenschmidt , Luis Rodriguez , Konrad Rzeszutek Wilk , "linux-kernel@vger.kernel.org" , Stefan Bader , Andy Lutomirski , Linux MM , Ralf Baechle , Henrique de Moraes Holschuh , Michael Ellerman , Tejun Heo , Paul Mackerras , Russell King - ARM Linux , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1597 Lines: 34 On Wed, Jul 1, 2015 at 8:23 AM, Christoph Hellwig wrote: >> One useful feature of the ifdef mess as implemented in the patch is >> that you could test for whether ioremap_cache() is actually >> implemented or falls back to default ioremap(). I think for >> completeness archs should publish an ioremap type capabilities mask >> for drivers that care... (I can imagine pmem caring), or default to >> being permissive if something like IOREMAP_STRICT is not set. There's >> also the wrinkle of archs that can only support certain types of >> mappings at a given alignment. > > I think doing this at runtime might be a better idea. E.g. a > ioremap_flags with the CACHED argument will return -EOPNOTSUP unless > actually implemented. On various architectures different CPUs or > boards will have different capabilities in this area. So it would be the responsibility of the caller to fall back from ioremap(..., CACHED) to ioremap(..., UNCACHED)? I.e. all drivers using it should be changed... Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- 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/