From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 92CBBC10F0E for ; Thu, 4 Apr 2019 19:52:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6C7C52171F for ; Thu, 4 Apr 2019 19:52:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730456AbfDDTwM (ORCPT ); Thu, 4 Apr 2019 15:52:12 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:33106 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728743AbfDDTwL (ORCPT ); Thu, 4 Apr 2019 15:52:11 -0400 Received: by atrey.karlin.mff.cuni.cz (Postfix, from userid 512) id BD3CD8029F; Thu, 4 Apr 2019 21:51:59 +0200 (CEST) Date: Thu, 4 Apr 2019 21:52:10 +0200 From: Pavel Machek To: Nick Crews Cc: enric.balletbo@collabora.com, bleung@chromium.org, linux-leds@vger.kernel.org, jacek.anaszewski@gmail.com, alexandre.belloni@bootlin.com, a.zummo@towertech.it, linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org, dlaurie@chromium.org, sjg@google.com, groeck@google.com, dtor@google.com Subject: Re: [PATCH v5 2/3] platform/chrome: Add Wilco EC keyboard backlight LEDs support Message-ID: <20190404195210.GC29984@amd> References: <20190404171007.160878-1-ncrews@chromium.org> <20190404171007.160878-2-ncrews@chromium.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="/Uq4LBwYP4y1W6pO" Content-Disposition: inline In-Reply-To: <20190404171007.160878-2-ncrews@chromium.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --/Uq4LBwYP4y1W6pO Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu 2019-04-04 11:10:08, Nick Crews wrote: > The EC is in charge of controlling the keyboard backlight on > the Wilco platform. We expose a standard LED class device at > /sys/class/leds/platform::kbd_backlight. This driver is modeled > after the standard Chrome OS keyboard backlight driver at > drivers/platform/chrome/cros_kbd_led_backlight.c >=20 > Some Wilco devices do not support a keyboard backlight. This > is checked via wilco_ec_keyboard_leds_exist() in the core driver, > and a platform_device will only be registered by the core if > a backlight is supported. >=20 > After an EC reset the backlight could be in a non-PWM mode. > Earlier in the boot sequence the BIOS should send a command to > the EC to set the brightness, so things **should** be set up, > but we double check in probe() as we query the initial brightness. > If not set up, then set the brightness to 0. >=20 > Since the EC will never change the backlight level of its own accord, > we don't need to implement a brightness_get() method. =2E.. > Signed-off-by: Nick Crews > Acked-by: Jacek Anaszewski Acked-by: Pavel Machek --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --/Uq4LBwYP4y1W6pO Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAlymYGoACgkQMOfwapXb+vLYUgCgsPgTBohHm4ztKgBYMtWoJma0 VRkAoI4/89nZFkwhMdJlDvcCK+hHhMyL =c7Go -----END PGP SIGNATURE----- --/Uq4LBwYP4y1W6pO--