From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH v3 2/3] ACPI / OSL: Allow PCI to be disabled Date: Tue, 11 Dec 2018 23:51:39 +0100 Message-ID: References: <20181210181315.5023-1-okaya@kernel.org> <20181210181315.5023-2-okaya@kernel.org> <20181211170957.GA335@infradead.org> <342c5dd9-cb3d-d714-c87f-814a942cf395@kernel.org> <6644defb-9199-6467-6e3e-8ce552b56f87@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: <6644defb-9199-6467-6e3e-8ce552b56f87@kernel.org> Sender: linux-kernel-owner@vger.kernel.org To: okaya@kernel.org Cc: "Rafael J. Wysocki" , Christoph Hellwig , ACPI Devel Maling List , "Rafael J. Wysocki" , Len Brown , Linux Kernel Mailing List List-Id: linux-acpi@vger.kernel.org On Tue, Dec 11, 2018 at 11:22 PM Sinan Kaya wrote: > > On 12/11/2018 5:16 PM, Rafael J. Wysocki wrote: > >> AFAIK, ACPI spec says that AML code running on non-existing op-regions to be > >> discarded last time I checked. > > I guess you mean "disregarded"? > > > > I have seen Linux complain about reads/writes to non-existing I2C opregions > before as a read/write failure for every single AML transaction. I was under the > impression that we didn't care. > > > So the spec appears to expect the OS to silently ignore the failures > > in those cases, so why should an error be returned? > > > > I can certainly return success for this case when CONFIG_PCI is not present. > > >> I know Linux is noisy about these. Well, users running kernels with CONFIG_PCI unset on platforms expecting PCI support to be present in the OS may want to know that I suppose, so that would be a good reason to return an error, but perhaps just once rather than on every access (maybe unless debugging is enabled?).