linux-kernel - Re: [PATCH v9 5/7] ACPI: Translate the I/O range of non-MMIO devices before scanning

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Message-ID: <20170613084831.GP3187@lahna.fi.intel.com>
Date:   Tue, 13 Jun 2017 11:48:31 +0300
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc:     Gabriele Paoloni <gabriele.paoloni@...wei.com>, rafael@...nel.org,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "will.deacon@....com" <will.deacon@....com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "frowand.list@...il.com" <frowand.list@...il.com>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "arnd@...db.de" <arnd@...db.de>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "brian.starkey@....com" <brian.starkey@....com>,
        "olof@...om.net" <olof@...om.net>,
        "benh@...nel.crashing.org" <benh@...nel.crashing.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        Linuxarm <linuxarm@...wei.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "minyard@....org" <minyard@....org>,
        John Garry <john.garry@...wei.com>,
        "xuwei (O)" <xuwei5@...ilicon.com>
Subject: Re: [PATCH v9 5/7] ACPI: Translate the I/O range of non-MMIO devices
 before scanning

On Mon, Jun 12, 2017 at 04:57:00PM +0100, Lorenzo Pieralisi wrote:
> I had a more in-depth look at this series and from my understanding
> the problem are the following to manage the LPC bindings in ACPI.
> 
> (1) Child devices of an LPC controller require special handling when
>     filling their resources (ie they need to be translated - in DT
>     that's guaranteed by the "isa" binding, in ACPI it has to be
>     done by new code)
> (2) In DT systems, LPC child devices are created by the LPC bus
>     controller driver through an of_platform_populate() call with
>     the LPC controller node as the fwnode root. For ACPI to work
>     the same way there must be a way to prevent LPC children to
>     be enumerated in acpi_default_enumeration() something like
>     I2C does (and then the LPC driver would enumerate its children as
>     DT does)
> 
> I am not sure how (1) and (2) can be managed with current ACPI bindings
> and kernel code - I suspect it may be done by mirroring what's done
> for I2C but I am not sure, that's why I CC'ed Mika (ie the LPC adapter
> is matched as a platform device and it takes care of enumerating its
> children - problem though is preventing enumeration from core ACPI code).

Is there an example ASL showing how these LPC devices are
currently presented in ACPI?