linux-kernel - Re: [PATCH v5 07/11] platform/x86: int3472: Split into 2 drivers

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Message-ID: <8eaeca66-f719-6b5d-bd7c-ccbd15a0b91c@redhat.com>
Date:   Tue, 2 Nov 2021 15:24:01 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Mark Gross <markgross@...nel.org>,
        Andy Shevchenko <andy@...radead.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Daniel Scally <djrscally@...il.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, Len Brown <lenb@...nel.org>,
        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>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Kate Hsuan <hpa@...hat.com>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>
Subject: Re: [PATCH v5 07/11] platform/x86: int3472: Split into 2 drivers

Hi,

On 11/2/21 15:16, Andy Shevchenko wrote:
> On Tue, Nov 2, 2021 at 11:49 AM Hans de Goede <hdegoede@...hat.com> wrote:
>>
>> The intel_skl_int3472.ko module contains 2 separate drivers,
>> the int3472_discrete platform driver and the int3472_tps68470
>> I2C-driver.
>>
>> These 2 drivers contain very little shared code, only
>> skl_int3472_get_acpi_buffer() and skl_int3472_fill_cldb() are
>> shared.
>>
>> Split the module into 2 drivers, linking the little shared code
>> directly into both.
>>
>> This will allow us to add soft-module dependencies for the
>> tps68470 clk, gpio and regulator drivers to the new
>> intel_skl_int3472_tps68470.ko to help with probe ordering issues
>> without causing these modules to get loaded on boards which only
>> use the int3472_discrete platform driver.
>>
>> While at it also rename the .c and .h files to remove the
>> cumbersome intel_skl_int3472_ prefix.
> 
> ...
> 
>> +union acpi_object *skl_int3472_get_acpi_buffer(struct acpi_device *adev, char *id)
>> +{
>> +       struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
>> +       acpi_handle handle = adev->handle;
>> +       union acpi_object *obj;
>> +       acpi_status status;
>> +
>> +       status = acpi_evaluate_object(handle, id, NULL, &buffer);
>> +       if (ACPI_FAILURE(status))
>> +               return ERR_PTR(-ENODEV);
>> +
>> +       obj = buffer.pointer;
>> +       if (!obj)
>> +               return ERR_PTR(-ENODEV);
>> +
>> +       if (obj->type != ACPI_TYPE_BUFFER) {
>> +               acpi_handle_err(handle, "%s object is not an ACPI buffer\n", id);
> 
>> +               kfree(obj);
> 
> I'm wondering if we should use more of the ACPI_FREE() calls as
> opposed to ACPI_ALLOCATE_BUFFER. Ditto for all such cases.

Basically the situation surrounding this is a mess, most code seems to
simply use plain kfree() which I find much more readable, but some
code indeed is using ACPI_FREE(), which I believe is really mostly
meant for internal use by the acpica code.

Eitherway until one of the ACPI maintainers clearly states
that we really should use ACPI_FREE() here I plan to stick with kfree()
because:

1. I find it much more readable.
2. AFAICT ACPI_FREE() is meant for acpica internal use
   (basically it is part of the OS abstraction bits of acpica)

Regards,

Hans