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: <CAHp75VccwpesvDxMcxZ+349rhrAq8QxNoau9XmquMnv9DBLBfA@mail.gmail.com>
Date:   Tue, 4 Jul 2017 18:46:59 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Gabriele Paoloni <gabriele.paoloni@...wei.com>
Cc:     Mika Westerberg <mika.westerberg@...ux.intel.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        "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 Tue, Jul 4, 2017 at 6:14 PM, Gabriele Paoloni
<gabriele.paoloni@...wei.com> wrote:

>> > In my case I'd like to have a platform device using the resources
>> that are
>> > parsed from the ACPI table (i.e. as it is done now by
>> > acpi_create_platform_device()).
>>
>> So far so good. Nothing prevents you to do that.
>>
>> > If my understanding is correct, if I declared an mfd_cell for my IPMI
>> child
>> > the mfd subsystem would create a platform device for such child and
>> > therefore acpi_create_platform_device() would fail to create a new
>> platform
>> > device as adev->physical_node_count will be non zero.
>> > However as things stand now mfd_cell devices can only use the
>> resources
>> > that are statically defined in the code (and therefore not the ones
>> in the
>> > ACPI nodes)...am I right?
>>
>> You may file resources first and then register MFD cells. See many
>> existing examples in the kernel.
>
> Well I had a look around the Kernel I have seen no mfd cells using
> Resources that are not statically defined:
> i.e. cell->resources in mfd_add_device() always points to statically
> defined resource structures.
>
> Usually for ACPI devices first you need to parse the ACPI resources
> from the table calling acpi_dev_get_resources(), then you iterate
> over the resource list and fill the resource array by calling
> acpi_platform_fill_resurces() (as in acpi_create_platform_device())
>
> With respect to my case are you suggesting dynamically allocate a
> resource array and fill it using the same fashion as
> acpi_create_platform_device(), then point cell->resources to such
> array before calling mfd_add_device() ?

You may do it on stack. Define your cell statically (but not const)
and apply resources just before mfd_add_devices() call.
There are examples in the existing drivers. Intel LPC comes to my mind
and perhaps PMC (Broxton), though latter has too much other stuff
around.

-- 
With Best Regards,
Andy Shevchenko