From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chen Gang Subject: Re: [PATCH] include/asm-generic/io.h: add 'UML' case just like 'no-MMU' Date: Wed, 26 Jun 2013 18:22:08 +0800 Message-ID: <51CAC0D0.60505@asianux.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51CABFAC.1040505@nod.at> Sender: linux-kernel-owner@vger.kernel.org To: Richard Weinberger Cc: Chen Gang , 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 List-Id: linux-arch.vger.kernel.org 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. 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 Asianux Corporation From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from intranet.asianux.com ([58.214.24.6]:24763 "EHLO intranet.asianux.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751583Ab3FZKXC (ORCPT ); Wed, 26 Jun 2013 06:23:02 -0400 Message-ID: <51CAC0D0.60505@asianux.com> Date: Wed, 26 Jun 2013 18:22:08 +0800 From: Chen Gang MIME-Version: 1.0 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> In-Reply-To: <51CABFAC.1040505@nod.at> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Richard Weinberger Cc: Chen Gang , 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 Message-ID: <20130626102208.EdRJMV09GzRESZgoo9GJL5BgnKXNw4mqoq4mMaNEOdc@z> 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. 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 Asianux Corporation