From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751473AbcFFMCk (ORCPT ); Mon, 6 Jun 2016 08:02:40 -0400 Received: from comal.ext.ti.com ([198.47.26.152]:39561 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751081AbcFFMCi (ORCPT ); Mon, 6 Jun 2016 08:02:38 -0400 Subject: Re: [PATCH] backlight: pwm_bl: disable PWM when 'duty_cycle' is zero To: =?UTF-8?Q?Lothar_Wa=c3=9fmann?= , Jean-Christophe Plagniol-Villard , Jingoo Han , Lee Jones , Thierry Reding , , , References: <1465209896-10319-1-git-send-email-LW@KARO-electronics.de> From: Tomi Valkeinen Message-ID: <5755664D.5070109@ti.com> Date: Mon, 6 Jun 2016 15:02:21 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-Version: 1.0 In-Reply-To: <1465209896-10319-1-git-send-email-LW@KARO-electronics.de> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="kNuhR8o4WgBv2Rl2lSIDJivXn71Fon0ro" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --kNuhR8o4WgBv2Rl2lSIDJivXn71Fon0ro Content-Type: multipart/mixed; boundary="U29awtVD8qFXqbilhIq0eSj4vCNXjmApt" From: Tomi Valkeinen To: =?UTF-8?Q?Lothar_Wa=c3=9fmann?= , Jean-Christophe Plagniol-Villard , Jingoo Han , Lee Jones , Thierry Reding , linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pwm@vger.kernel.org Message-ID: <5755664D.5070109@ti.com> Subject: Re: [PATCH] backlight: pwm_bl: disable PWM when 'duty_cycle' is zero References: <1465209896-10319-1-git-send-email-LW@KARO-electronics.de> In-Reply-To: <1465209896-10319-1-git-send-email-LW@KARO-electronics.de> --U29awtVD8qFXqbilhIq0eSj4vCNXjmApt Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Hi, On 06/06/16 13:44, Lothar Wa=C3=9Fmann wrote: > 'brightness' is usually an index into a table of duty_cycle values, > where the value at index 0 may well be non-zero > (tegra30-apalis-eval.dts and tegra30-colibri-eval-v3.dts are real-life > examples). > Thus brightness =3D=3D 0 does not necessarily mean that the PWM output > will be inactive. > Check for 'duty_cycle =3D=3D 0' rather than 'brightness =3D=3D 0' to de= cide > whether to disable the PWM. The binding doc does say: - brightness-levels: Array of distinct brightness levels. Typically the= se are in the range from 0 to 255, but any range starting at 0 will do= =2E The actual brightness level (PWM duty cycle) will be interpolated from these values. 0 means a 0% duty cycle (darkest/off), while the= last value in the array represents a 100% duty cycle (brightest). Tomi --U29awtVD8qFXqbilhIq0eSj4vCNXjmApt-- --kNuhR8o4WgBv2Rl2lSIDJivXn71Fon0ro Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJXVWZOAAoJEPo9qoy8lh71rlUP/1LZ7du57I/I2DqYuSQt+rzB 7Qjmu5i0Tr2XKLcX7Pxh3LgWETurlCvO0NILjjFbiBR8kr3rXVD9IcYx//cHAfWS qbjZcSNFhPYoXmMMabBT8SfBzeYjIGZJvqcRrd/9Pthft55giTJlCbO0jldkgmmL pou6sMM41YLY3024l5xeMtlD5qrh7WSUtzesDcyH/r0Nw3npwIQLz6frhz+MuZ3D k4YwGnPDqG2g+Aj8uqLAiL76DboNrnYl67/PcckGOWRQEXYbY4BzZl/VwY+0SFIN c9JfNFkQ253fFgO2F4NdL0pYsYktrkWw+YOqn2qPzQvISwOLsHrQe+BSGGRjbgmD pBpihPOQtELqudH6HZSle3U5+FsKwW+9CD6YaMjX4e8PUkSURoBXEhj6SbY5e/cC QlO5m2uckiTaSc4H/pccQCT/oQboHvCBYxaj3D9VgPbvRGzuZ0pVYOSeEOSVY596 KAXUTPOsciY9i5Xjj/46wSOlyH3EzKGW5gn9srcz+59pJXVJHtrezcrxEBWFGBj1 tKoEyPOyO/kH/LnI3iehEDztLPYWo+hcUrU1QL8tggnrbmvbl2EsFL84LiPYvng4 3WvrvIL+Cuy60OuszyTuB2GSi9kM+KVoht2ESkCb5NTUETU3AgslF/QhTb5R0Dmn zqDKyCyfUtmch1+Pa/Hf =ZpVl -----END PGP SIGNATURE----- --kNuhR8o4WgBv2Rl2lSIDJivXn71Fon0ro--