From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423588Ab2KOGvs (ORCPT ); Thu, 15 Nov 2012 01:51:48 -0500 Received: from moutng.kundenserver.de ([212.227.126.171]:49566 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752326Ab2KOGvq (ORCPT ); Thu, 15 Nov 2012 01:51:46 -0500 Date: Thu, 15 Nov 2012 07:51:40 +0100 From: Thierry Reding To: Jingoo Han Cc: "'Andrew Morton'" , "'Richard Purdie'" , "'Florian Tobias Schandinat'" , linux-fbdev@vger.kernel.org, devicetree-discuss@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] backlight: Add of_find_backlight_by_node() function Message-ID: <20121115065140.GA21208@avionic-0098.mockup.avionic-design.de> References: <1352469878-4532-1-git-send-email-thierry.reding@avionic-design.de> <004201cdc2d0$c1920210$44b60630$%han@samsung.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="d6Gm4EdcadzBjdND" Content-Disposition: inline In-Reply-To: <004201cdc2d0$c1920210$44b60630$%han@samsung.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Provags-ID: V02:K0:aTXWw5AtTPJVVu0aaN/AKH+YysOK7nwRpzbyQgU5OSe hHCqtqHU3+j9tJiRD1mSrRyzmeJroXfgpO1rMxJ2PbA2j47YdI re+2ip34qN6v5ISsBggdyjmePScRxrcfVUqNexymIYQNeW5PLd YQ7t39NUvTypHhnP7o3bPhtov4KccXkd5TVzFZE/RFLq3JIIQz JARHiGMRhpp/Bc8omLL7u0Io1vbrh7wwTNgjTSeg8b+kezJZaL PRfvH871a1hWob6a/FMOvlFNhGSX5Mu7rUT3TcZTMCURej3qA2 /plpt8cN5mC3dyP1ny7LIdS9av5F/t6PdeqYd4MusphEJP/z9V qL7oho+cosjUa9HWDt5SnrShvCPJUbNLx36q+jilsQiqL8/s/0 9glPrA+7Fq5t1REb53JUNk61uD031NkOhs= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --d6Gm4EdcadzBjdND Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Nov 15, 2012 at 10:30:11AM +0900, Jingoo Han wrote: > On Friday, November 09, 2012 11:05 PM Thierry Reding wrote > >=20 > > This function finds the struct backlight_device for a given device tree > > node. A dummy function is provided so that it safely compiles out if OF > > support is disabled. > >=20 > > Signed-off-by: Thierry Reding >=20 > CC'ed Andrew Morton Yes, the backlight subsystem isn't very well maintained, so I should have added Andrew in the first place. Thanks. >=20 > Hi Thierry Reding, >=20 > The patch itself looks good. > Could you explain when this API is used? > Thank you. I use this for the upcoming Tegra DRM driver in order to hook up the backlight with the DRM driver via DT to allow switching off the backlight when the corresponding DRM output is switched of using DPMS. Basically what you have is something like this in the device tree: display { ... backlight =3D <&backlight>; ... } Then you call something along these lines: np =3D of_parse_phandle(display, "backlight", 0); if (np) { backlight =3D of_find_backlight_by_node(np); of_node_put(np); } And then use the standard backlight API on the returned pointer. Thierry --d6Gm4EdcadzBjdND Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iQIcBAEBAgAGBQJQpJD8AAoJEN0jrNd/PrOha78QAKrmB5kcDGsvG3yUD2UzLQEN ojO/wQfxoXtz1em03YT0QcPsQX+RL4PEx8VMLF+lHzwNEWqTaiJozeidhhi7LeHk rKbQoDlwJWCGMW6zU/V09V/W/0hBxExl3NniA/LY5tmCyxnneRoWRMve8JpOmcWm R6SVrmpr3AFupbcqsDnzSfDDQ/LpDgRA27vkI12LyVr9TCjgOZDvu+iJGlKbgwUQ tlviqfkTCYsRHIYJiIZLf6Gsf0A08t0F4LTiSExRksHWqDSJU3urcNE39XAP/rk1 rmxKjzfXbzaXK7tyCqL/RyCJ++KFfk6951GT5bMxg6HThnROg9yyUU9zCzFjrV7J KHLJrZ7b8IqOwNMEeSKDOXlhVkxUCIzkgxsQz8tTB0gWtZEVFI76MO3hv97Tn3Ua u4crQ3cJSKZzziGCPlWB1Mx3KHAbHPnircLqKlaEUuqwN7ITxM3nlCra6NlyCoVy hYj6KCI4cQuEOlWfyy1zpwVbCfFmTOkw/5Kahi7CrlccmXqUPrwYeiTTGGo2De1Y 8hGB3IUmxttGsLly4wtiGPPEN7QZrF3pyporlUu4mY2Eu16pGAYHq8S+O0IVqE0O vPDtrfNatT9A5mgHykAy7k0GA5Gx+mh5aGsKGGj9iXhQLuzVogc4R/mpsmD+uCtR 8bQcShL4Zk/fIVTwOQNS =11EW -----END PGP SIGNATURE----- --d6Gm4EdcadzBjdND--