Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752440Ab3GADoy (ORCPT ); Sun, 30 Jun 2013 23:44:54 -0400 Received: from intranet.asianux.com ([58.214.24.6]:37396 "EHLO intranet.asianux.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751864Ab3GADow (ORCPT ); Sun, 30 Jun 2013 23:44:52 -0400 X-Spam-Score: -106.8 Message-ID: <51D0FAFE.5010500@asianux.com> Date: Mon, 01 Jul 2013 11:43:58 +0800 From: Chen Gang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: Chen Gang CC: Richard Weinberger , Geert Uytterhoeven , Jeff Dike , Arnd Bergmann , David Sharp , "sfr@canb.auug.org.au" , Steven Rostedt , Ingo Molnar , uml-devel , uml-user , "linux-kernel@vger.kernel.org" , Linux-Arch , Mark Brown , David Miller Subject: Re: [PATCH] include/asm-generic/io.h: add 'UML' case just like 'no-MMU' References: <51CA8AB8.7080504@asianux.com> <51CA900E.9020407@nod.at> <51CA9E92.4000107@asianux.com> <51CAA0C6.60007@nod.at> <51CAA78C.5040900@asianux.com> <51CAA8D6.9000505@nod.at> <51CAAD1D.8050801@asianux.com> <51CAAE7C.9090003@nod.at> <51CAB556.4070700@asianux.com> <51CAB689.70008@nod.at> <51CABBDD.403@asianux.com> <51CABFAC.1040505@nod.at> <51CAC0D0.60505@asianux.com> <51D0DE09.4090702@asianux.com> In-Reply-To: <51D0DE09.4090702@asianux.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4237 Lines: 102 On 07/01/2013 09:40 AM, Chen Gang wrote: > On 06/26/2013 06:22 PM, Chen Gang wrote: >> > On 06/26/2013 06:17 PM, Richard Weinberger wrote: >>> >> Am 26.06.2013 12:01, schrieb Chen Gang: >>>>> >>>> On 06/26/2013 05:48 PM, Geert Uytterhoeven wrote: >>>>>>> >>>>>> On Wed, Jun 26, 2013 at 11:38 AM, Richard Weinberger wrote: >>>>>>>>>>>>>>> >>>>>>>>>>>>>> Since the API itself already contents the meaning: "return NULL means >>>>>>>>>>>>>>> >>>>>>>>>>>>>> the arch has no related io memory", >>>>>>> >>>>>> No, NULL means it could not map the I/O memory. >>>>>>> >>>>>> >>>>> >>>> >>>>> >>>> "it could not map the I/O memory" includes "has no related io memory". >>>>> >>>> So it is enough for our case. >>>>> >>>> >>>>>>>>>>>>>>> >>>>>>>>>>>>>> Why not define a generic dummy one in "include/asm-generic/io.h" instead >>>>>>>>>>>>>>> >>>>>>>>>>>>>> of "HAS_IOMEM" (which has already spread many various places, and also, >>>>>>>>>>>>>>> >>>>>>>>>>>>>> most of new drivers have to know about it). >>>>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>>>> >>>>>>>>>>>>>> e.g: in "include/asm-generic/io.h", if "CONFIG_HAS_IOMEM=n", define a >>>>>>>>>>>>>>> >>>>>>>>>>>>>> dummy ioremap() which return NULL ... (also need consider more details). >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>>> >>>>>>>>>> Because we don't even want to build these drivers and not make them fail while >>>>>>>>>>> >>>>>>>>>> executing io memory related functions. >>>>>>> >>>>>> Indeed, it doesn't make sense to build drivers that cannot work. >>>>>>> >>>>>> And they may fail in a very bad way. >>>>> >>>> >>>>> >>>> That is our 'platform' guys feeling, not the 'module' guys, as >>>>> >>>> 'platform' guys, it is better to provide the choice to 'module' guys, >>>>> >>>> and let them decide by themselves, not forced by us. >>> >> FYI, this is my last reply to this thread. >>> >> >>> >> As Geert and I said, drivers which need io memory have to depend on HAS_IOMEM=y. >>> >> If an arch does not have io memory these drivers cannot work and therefore we don't >>> >> want them built. >> > > Hmm, if the modules select 'COMPILE_TEST', it is better to let asm-generic > support this features (at least, not forbid it) > > So how about the diff below ? ;-) > > ---------------------------diff begin----------------------------------- > > diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h > index d5afe96..ede3775 100644 > --- a/include/asm-generic/io.h > +++ b/include/asm-generic/io.h > @@ -303,13 +303,17 @@ static inline void *phys_to_virt(unsigned long address) > /* > * Change "struct page" to physical address. > * > - * This implementation is for the no-MMU case only... if you have an MMU > - * you'll need to provide your own definitions. > + * This for the no-MMU, or no-IOMEM but still try to COMPILE_TEST cases. > + * if you have an MMU and IOMEM, you'll need to provide your own definitions. > */ > -#ifndef CONFIG_MMU > +#if !defined(CONFIG_MMU) || \ > + (!defined(CONFIG_HAS_IOMEM) && defined(COMPILE_TEST)) Need use 'CONFIG_COMPILE_TEST' instead of 'COMPILE_TEST'. > static inline void __iomem *ioremap(phys_addr_t offset, unsigned long size) > { > +#if !defined(CONFIG_MMU) > return (void __iomem*) (unsigned long)offset; > +#else > + return NULL; > } > > #define __ioremap(offset, size, flags) ioremap(offset, size) > @@ -325,7 +329,7 @@ static inline void __iomem *ioremap(phys_addr_t offset, unsigned long size) > static inline void iounmap(void __iomem *addr) > { > } > -#endif /* CONFIG_MMU */ > +#endif /* !MMU || (!HAS_IOMEM && COMPILE_TEST) */ > > #ifdef CONFIG_HAS_IOPORT > #ifndef CONFIG_GENERIC_IOMAP > > ---------------------------diff end------------------------------------- > >> > It is really the time for stopping discussion, and thank you all for >> > spending your time resources on this discussion. >> > >> > Next, I will send related patch for it (also cc to you all). >> > >> > >> > Thanks. >> > > > -- Chen Gang > -- Chen Gang -- 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/