linux-kernel - Re: [PATCH v13 7/9] ACPI: Translate the I/O range of non-MMIO devices before scanning

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Date:   Wed, 14 Feb 2018 18:16:53 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     John Garry <john.garry@...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>,
        Hanjun Guo <hanjun.guo@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Arnd Bergmann <arnd@...db.de>,
        Mark Rutland <mark.rutland@....com>,
        Olof Johansson <olof@...om.net>,
        Dann Frazier <dann.frazier@...onical.com>,
        Rob Herring <robh@...nel.org>, Joe Perches <joe@...ches.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        linux-pci@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linuxarm <linuxarm@...wei.com>, Corey Minyard <minyard@....org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux-Arch <linux-arch@...r.kernel.org>,
        Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH v13 7/9] ACPI: Translate the I/O range of non-MMIO devices
 before scanning

On Wed, Feb 14, 2018 at 5:33 PM, John Garry <john.garry@...wei.com> wrote:
> On 14/02/2018 13:53, Andy Shevchenko wrote:
>> On Tue, Feb 13, 2018 at 7:45 PM, John Garry <john.garry@...wei.com> wrote:

>>> +       sys_port = logic_pio_trans_hwaddr(&host->fwnode, res->start,
>>> len);
>>> +       if (sys_port == -1UL)

>> Wouldn't it be better to compare with ULONG_MAX?

> Could do, being the same thing. Maybe people prefer -1UL as it saves having
> to figure out what ULONG_MAX is :)

-1UL looks confusing.

Another approach is to use ~0UL if that is preferable.

>>> +       list_for_each_entry(rentry, &resource_list, node)
>>> +               resources[count++] = *rentry->res;

>> It has similarities with acpi_create_platform_device().
>> I guess we can utilize existing code.

> For sure, this particular segment is effectively same as part of
> acpi_create_platform_device():

Not the same, acpi_create_platform_device() does a bit more than
copying the resources. If it indeed makes no hurt...

>         list_for_each_entry(rentry, &resource_list, node)
>             acpi_platform_fill_resource(adev, rentry->res,
>                             &resources[count++]);

> So is your idea to refactor this common segment into a helper function?

...I would go with helper.

>>> +               char *name = &acpi_indirect_io_mfd_cell[count].name[0];
>>> +               char *pnpid = &acpi_indirect_io_mfd_cell[count].pnpid[0];
>>
>>
>> Plain x is equivalent to &x[0].

> Right, but I thought for arrays that we should use address of x rather than
> x itself, no?

x is addressed by it's beginning.

-- 
With Best Regards,
Andy Shevchenko