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Date:   Thu, 5 May 2022 10:25:12 +0200
From:   Pavel Machek <pavel@ucw.cz>
To:     Manuel =?iso-8859-1?Q?Sch=F6nlaub?= <manuel.schoenlaub@gmail.com>
Cc:     lains@riseup.net, jikos@kernel.org, benjamin.tissoires@redhat.com,
        linux-input@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] HID: logitech-hidpp: support Color LED feature (8071).
Message-ID: <20220505082512.GA14065@duo.ucw.cz>
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Hi!

> > > The HID++ protocol allows to set multicolor (RGB) to a static color.
> > > Multiple of such LED zones per device are supported.
> > > This patch exports said LEDs so that they can be set from userspace.
> > >=20
> > > Signed-off-by: Manuel Sch=F6nlaub <manuel.schoenlaub@gmail.com>
> >=20
> > Please cc LEDs stuff to the LED lists.
> >=20
>=20
> Will do. Though it seems like first we should discuss whether the kernel
> in fact is the right place, no?

Well, on embedded systems keyboard backlight is handled in kernel.

> > > +	cdev =3D &mc_dev->led_cdev;
> > > +	cdev->name =3D devm_kasprintf(&hdev->dev, GFP_KERNEL,
> > > +				    "%s:rgb:indicator-%d", hdev->uniq, zone);
> >=20
> > So this is keyboard backlight? We should add the documentation at the
> > very least, so that other drivers use same name.
>=20
> I do not own a Logitech keyboard, but some mice. There are RGB leds
> that you can normally control with Windows software.
>=20
> I'd suppose (but could not verify) that supported keyboards by Logitech
> work with the same feature.

And I guess we should do the same for Logitech keyboards. Userspace
does not need to go to /sys/class/gpio... to control keyboard
backlight on Nokia cellphone, it should not need to talk USB directly
to control backlight on Logitech keyboards.

Best regards,
								Pavel
--=20
People of Russia, stop Putin before his war on Ukraine escalates.

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