linux-kernel - Re: [PATCH v5 1/4] ACPI / scan: Initialize status to ACPI_STA

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Date:   Thu, 9 Aug 2018 11:39:47 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Darren Hart <dvhart@...radead.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        linux-i2c <linux-i2c@...r.kernel.org>
Subject: Re: [PATCH v5 1/4] ACPI / scan: Initialize status to ACPI_STA_DEFAULT

Hi,

On 09-08-18 11:35, Rafael J. Wysocki wrote:
> On Thu, Aug 9, 2018 at 11:15 AM, Hans de Goede <hdegoede@...hat.com> wrote:
>> Since commit 63347db0affa ("ACPI / scan: Use acpi_bus_get_status() to
>> initialize ACPI_TYPE_DEVICE devs") the status field of normal acpi_devices
>> gets set to 0 by acpi_bus_type_and_status() and filled with its actual
>> value later when acpi_add_single_object() calls acpi_bus_get_status().
>>
>> This means that any acpi_match_device_ids() calls in between will always
>> fail with -ENOENT.
>>
>> We already have a workaround for this, which temporary forces status to
>> ACPI_STA_DEFAULT in drivers/acpi/x86/utils.c: acpi_device_always_present()
>> and the next commit in this series adds another acpi_match_device_ids()
>> call between status being initialized as 0 and the acpi_bus_get_status()
>> call.
>>
>> Rather then adding another workaround, this commit makes
>> acpi_bus_type_and_status() initialize status to ACPI_STA_DEFAULT, this is
>> safe to do as the only code looking at status between the initialization
>> and the acpi_bus_get_status() call is those acpi_match_device_ids() calls.
>>
>> Note this does mean that we need to (re)set status to 0 in case the
>> acpi_bus_get_status() call fails.
>>
>> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
>> ---
>> Changes in v3:
>> -New patch in v3 of this patch-set
>>
>> Changes in v4:
>> -This is not a fix for acpi_is_indirect_io_slave() as I thought at first,
>>   acpi_is_indirect_io_slave() calls acpi_match_device_ids() on its parent
>>   device, where status is already set properly. Rewrite the commit message
>>   accordingly.
> 
> I've applied the v4 of this patch and I don't think there are any
> changes from it here.

Correct, there were only changes to the 4th patch in the series.

> As for the rest of the series I'll wait from comments from Wolfram and
> the other reviewers.

Ok, note if you've taken patch 1 you may also want to take patch 3 which
is an ACPI code cleanup made possible by patch 1 and otherwise is
unrelated.

Regards,

Hans