Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751386AbdDACRI (ORCPT ); Fri, 31 Mar 2017 22:17:08 -0400 Received: from mail-pf0-f196.google.com ([209.85.192.196]:33376 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751099AbdDACRF (ORCPT ); Fri, 31 Mar 2017 22:17:05 -0400 Subject: Re: [PATCH V8 5/6] ACPI: Support the probing on the devices which apply indirect-IO To: "Rafael J. Wysocki" , "zhichang.yuan" References: <1490887619-61732-1-git-send-email-yuanzhichang@hisilicon.com> <1490887619-61732-6-git-send-email-yuanzhichang@hisilicon.com> <1908501.jAQQKvjW4f@aspire.rjw.lan> <58DDFCBE.1030705@hisilicon.com> Cc: "Rafael J. Wysocki" , Catalin Marinas , Will Deacon , Rob Herring , Frank Rowand , Bjorn Helgaas , Arnd Bergmann , "linux-arm-kernel@lists.infradead.org" , Mark Rutland , Brian Starkey , Olof Johansson , Lorenzo Pieralisi , Benjamin Herrenschmidt , Linux Kernel Mailing List , ACPI Devel Maling List , linuxarm@huawei.com, "devicetree@vger.kernel.org" , Linux PCI , Corey Minyard , Zou Rongrong , John Garry , Gabriele Paoloni , kantyzc@163.com, xuwei5@hisilicon.com From: "zhichang.yuan" Message-ID: Date: Sat, 1 Apr 2017 10:16:53 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: 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: 1943 Lines: 46 On 04/01/2017 07:02 AM, Rafael J. Wysocki wrote: > On Fri, Mar 31, 2017 at 8:52 AM, zhichang.yuan > wrote: >> Hi, Rafael, >> >> Thanks for reviewing this! >> >> On 2017/3/31 4:31, Rafael J. Wysocki wrote: >>> On Thursday, March 30, 2017 11:26:58 PM zhichang.yuan wrote: >>>> On some platforms(such as Hip06/Hip07), the legacy ISA/LPC devices access I/O >>>> with some special host-local I/O ports known on x86. To access the I/O >>>> peripherals, an indirect-IO mechanism is introduced to mapped the host-local >>>> I/O to system logical/fake PIO similar the PCI MMIO on architectures where no >>>> separate I/O space exists. Just as PCI MMIO, the host I/O range should be >>>> registered before probing the downstream devices and set up the I/O mapping. >>>> But current ACPI bus probing doesn't support these indirect-IO hosts/devices. >>>> >>>> This patch introdueces a new ACPI handler for this device category. Through the >>>> handler attach callback, the indirect-IO hosts I/O registration is done and >>>> all peripherals' I/O resources are translated into logic/fake PIO before >>>> starting the enumeration. >>> >>> Can you explain to me briefly what exactly this code is expected to be doing? >> >> As you know currently for ARM architecture IO space is memory mapped and >> is only used by pci devices. The port number is dynamically allocated >> converting the device IO address into a PIO token: i.e. >> http://lxr.free-electrons.com/source/drivers/acpi/pci_root.c#L745 >> This patch is meant to support a new class of IO host controller >> that are not PCI based and that still require to have the IO addresses >> be translated in the same PIO token space as the PCI controller > > IOW, this is ARM-specific, right? Yes. The current host added in this patch with _HID "HISI0191" is on ARM64. But, I think the handler driver is architecture dependent. Thanks, Zhichang > > Thanks, > Rafael >