MIME-Version: 1.0
In-Reply-To: <58DDFCBE.1030705@hisilicon.com>
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>
From: "Rafael J. Wysocki" <rafael@kernel.org>
Date: Sat, 1 Apr 2017 01:02:32 +0200
Message-ID: <CAJZ5v0gZdghH7jjd-zMmqXNkuvVVVSPDHfBrJXx5OXR2NE0KgA@mail.gmail.com>
Subject: Re: [PATCH V8 5/6] ACPI: Support the probing on the devices which
 apply indirect-IO
To: "zhichang.yuan" <yuanzhichang@hisilicon.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>, Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Brian Starkey <brian.starkey@arm.com>, Olof Johansson <olof@lixom.net>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        linuxarm@huawei.com,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        Linux PCI <linux-pci@vger.kernel.org>, Corey Minyard <minyard@acm.org>,
        Zou Rongrong <zourongrong@gmail.com>,
        John Garry <john.garry@huawei.com>,
        Gabriele Paoloni <gabriele.paoloni@huawei.com>,
        zhichang.yuan02@gmail.com, kantyzc@163.com, xuwei5@hisilicon.com
Content-Type: text/plain; charset=UTF-8
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1692
Lines: 35

On Fri, Mar 31, 2017 at 8:52 AM, zhichang.yuan
<yuanzhichang@hisilicon.com> 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?

Thanks,
Rafael