linux-kernel - Re: [PATCH v5 19/19] auxdisplay: ht16k33: Add LED support

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Date:   Fri, 13 Aug 2021 14:52:52 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Marek Behún <kabel@...nel.org>,
        Robin van der Gracht <robin@...tonic.nl>,
        Miguel Ojeda <ojeda@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Paul Burton <paulburton@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Pavel Machek <pavel@....cz>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        linux-leds <linux-leds@...r.kernel.org>,
        "open list:BROADCOM NVRAM DRIVER" <linux-mips@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH v5 19/19] auxdisplay: ht16k33: Add LED support

Hi Andy,

On Thu, Aug 12, 2021 at 2:33 PM Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
> On Wednesday, August 11, 2021, Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>> On Wed, Aug 11, 2021 at 12:48 PM Marek Behún <kabel@...nel.org> wrote:
>> > On Wed, 11 Aug 2021 11:57:59 +0200
>> > Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>> > > Instantiate a single LED based on the "led" subnode in DT.
>> > > This allows the user to control display brightness and blinking (backed
>> > > by hardware support) through the LED class API and triggers, and exposes
>> > > the display color.  The LED will be named
>> > > "auxdisplay:<color>:<function>".
>> > >
>> > > When running in dot-matrix mode and if no "led" subnode is found, the
>> > > driver falls back to the traditional backlight mode, to preserve
>> > > backwards compatibility.
>> > >
>> > > Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
>> >
>> > Reviewed-by: Marek Behún <kabel@...nel.org>
>>
>> Thanks!
>>
>> > BTW, this driver does not need to depend on OF, methinks.
>> > The few instances of properties reading can be
>> > easily rewritten to device_* functions (from include/linux/property.h).
>> > The of_get_child_by_name() can become device_get_named_child_node().
>> >
>> > Geert, what do you think?
>>
>> Sure, that can be done later, when an ACPI user appears?
>
> Actually with PRP0001 approach any of compatible driver may be used onACPI platform. So, what you are saying can be interpreted the way “we don’t care about users on ACPI based platforms”. If it is the case, then it should be told explicitly.

I think you're interpreting too much ;-)
My point is simply:

>> The dependency on OF was pre-existing, and this series is already
>> at v5.

If any OF compatible driver can now be used on ACPI platforms, perhaps
this should be handled at the API level? I.e. the distinction between
OF and device properties should be dropped completely, and all drivers
be converted mechanically in one shot, instead of a gradual ad-hoc
conversion being sneaked in through other series like this one?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds