linux-kernel - Re: [PATCH v3 1/6] ACPI: scan: Extend acpi_walk_dep_device

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Message-ID: <3138da4c-7e1b-d75e-b0a3-014bdc5147c1@gmail.com>
Date:   Mon, 8 Mar 2021 20:49:40 +0000
From:   Daniel Scally <djrscally@...il.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Tomasz Figa <tfiga@...omium.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Rajmohan Mani <rajmohan.mani@...el.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Wolfram Sang <wsa@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <mgross@...ux.intel.com>,
        Maximilian Luz <luzmaximilian@...il.com>,
        Robert Moore <robert.moore@...el.com>,
        Erik Kaneda <erik.kaneda@...el.com>, me@...wu.ch,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        "open list:ACPI COMPONENT ARCHITECTURE (ACPICA)" <devel@...ica.org>
Subject: Re: [PATCH v3 1/6] ACPI: scan: Extend acpi_walk_dep_device_list()

Hi Rafael

On 08/03/2021 17:23, Rafael J. Wysocki wrote:
> On Mon, Mar 8, 2021 at 4:45 PM Rafael J. Wysocki <rafael@...nel.org> wrote:
>> On Mon, Mar 8, 2021 at 2:57 PM Andy Shevchenko
>> <andy.shevchenko@...il.com> wrote:
>>> On Mon, Mar 08, 2021 at 02:36:27PM +0100, Rafael J. Wysocki wrote:
>>>> On Sun, Mar 7, 2021 at 9:39 PM Andy Shevchenko
>>>> <andy.shevchenko@...il.com> wrote:
>>>>> On Sun, Mar 7, 2021 at 3:36 PM Daniel Scally <djrscally@...il.com> wrote:
>>>>>> On 22/02/2021 13:34, Andy Shevchenko wrote:
>>>>>>> On Mon, Feb 22, 2021 at 3:12 PM Daniel Scally <djrscally@...il.com> wrote:
>>>>>>>> The acpi_walk_dep_device_list() is not as generalisable as its name
>>>>>>>> implies, serving only to decrement the dependency count for each
>>>>>>>> dependent device of the input. Extend the function to instead accept
>>>>>>>> a callback which can be applied to all the dependencies in acpi_dep_list.
>>>>>>>> Replace all existing calls to the function with calls to a wrapper, passing
>>>>>>>> a callback that applies the same dependency reduction.
>>>>>>> The code looks okay to me, if it was the initial idea, feel free to add
>>>>>>> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
>>> ...
>>>
>>>>>>>> +void acpi_dev_flag_dependency_met(acpi_handle handle)
>>>>>>> Since it's acpi_dev_* namespace, perhaps it should take struct acpi_device here?
>>>>>> I can do this, but I avoided it because in most of the uses in the
>>>>>> kernel currently there's no struct acpi_device, they're just passing
>>>>>> ACPI_HANDLE(dev) instead, so I'd need to get the adev with
>>>>>> ACPI_COMPANION() in each place. It didn't seem worth it...
>>>> It may not even be possible sometimes, because that function may be
>>>> called before creating all of the struct acpi_device objects (like in
>>>> the case of deferred enumeration).
>>>>
>>>>>> but happy to
>>>>>> do it if you'd prefer it that way?
>>>>> I see, let Rafael decide then. I'm not pushing here.
>>>> Well, it's a matter of correctness.
>>> Looking at your above comment it is indeed. Thanks for clarification!
>> Well, actually, the struct device for the object passed to this
>> function should be there already, because otherwise it wouldn't make
>> sense to update the list.  So my comment above is not really
>> applicable to this particular device and the function could take a
>> struct acpi_device pointer argument.  Sorry for the confusion.
>>
>>> But should we have acpi_dev_*() namespace for this function if it takes handle?
>> It takes a device object handle.
>>
>> Anyway, as per the above, it can take a struct acpi_device pointer
>> argument in which case the "acpi_dev_" prefix should be fine.


OK, so the conclusion there is change the argument to a struct
acpi_device pointer and update all the uses.

>>> For time being nothing better than following comes to my mind:
>>>
>>> __acpi_dev_flag_dependency_met() => __acpi_flag_device_dependency_met()
>>> acpi_dev_flag_dependency_met() => acpi_flag_device_dependency_met()
>> The above said, the name is somewhat confusing overall IMV.
>>
>> Something like acpi_dev_clear_dependencies() might be better.
>>
>> So lets make it something like
>>
>> void acpi_dev_clear_dependencies(struct acpi_device *supplier);
> To be precise, there are two functions in the patch,
> acpi_dev_flag_dependency_met() which invokes
> acpi_walk_dep_device_list() and __acpi_dev_flag_dependency_met()
> invoked by the latter as a callback.
>
> Above I was talking about the first one.
>
> The callback should still take a struct acpi_dep_data pointer argument
> and I would call it acpi_scan_clear_dep() or similar.


OK, works for me, I'll make those changes - thanks