From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2993144Ab2KOI6k (ORCPT ); Thu, 15 Nov 2012 03:58:40 -0500 Received: from mailout1.samsung.com ([203.254.224.24]:16379 "EHLO mailout1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2992592Ab2KOI6h (ORCPT ); Thu, 15 Nov 2012 03:58:37 -0500 X-AuditID: cbfee61a-b7fa66d0000004cf-ce-50a4aebc5486 From: Jingoo Han To: "'Thierry Reding'" Cc: "'Andrew Morton'" , "'Richard Purdie'" , "'Florian Tobias Schandinat'" , linux-fbdev@vger.kernel.org, devicetree-discuss@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <1352469878-4532-1-git-send-email-thierry.reding@avionic-design.de> <004201cdc2d0$c1920210$44b60630$%han@samsung.com> <20121115065140.GA21208@avionic-0098.mockup.avionic-design.de> In-reply-to: <20121115065140.GA21208@avionic-0098.mockup.avionic-design.de> Subject: Re: [PATCH] backlight: Add of_find_backlight_by_node() function Date: Thu, 15 Nov 2012 17:58:35 +0900 Message-id: <001201cdc30f$65a17be0$30e473a0$%han@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7bit X-Mailer: Microsoft Office Outlook 12.0 Thread-index: Ac3C/bTVpgTGWvaYTTa9liMVzdC1FAAD4a1w Content-language: ko DLP-Filter: Pass X-MTR: 20000000000000000@CPGS X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrFIsWRmVeSWpSXmKPExsVy+t8zA90965YEGPxfKGhxou8Dq8XlXXPY HJg8Pm+SC2CM4rJJSc3JLEst0rdL4Mr4/ng/a8EhnopFq8+wNjAe5+xi5OSQEDCRmLl/BwuE LSZx4d56ti5GLg4hgWWMEj2XXzDDFL16eZEZIrGIUeJE5yYmkISQwC9GiXkXy0FsNgE1iS9f DrOD2CIC5hJLFu0Fa2AW+Moo0fikgQ2i4QijxMYP8V2MHBycAt4Sc/Zwg4SFBTwkNl/+ClbC IqAq0XkSZDEHB6+ArcT8V/ogYV4BQYkfk++BHcosoCWxfudxJghbXmLzmrdg5RIC6hKP/upC XGAkcWjtKUaIEhGJfS/eMUJMF5D4NvkQC0S5rMSmA2BHSghsYpeYu2IPI8S7khIHV9xgmcAo MQvJ5llINs9CsnkWkhULGFlWMYqmFiQXFCel5xrqFSfmFpfmpesl5+duYoREmNQOxpUNFocY BTgYlXh4HX4sDhBiTSwrrsw9xCjBwawkwhu1dkmAEG9KYmVValF+fFFpTmrxIUYfoMsnMkuJ JucDoz+vJN7Q2NjEzMTUxNzS1NwUh7CSOG+zR0qAkEB6YklqdmpqQWoRzDgmDk6pBsZY2aCE nVLfeJpWGx1KjwnsZ2M8oBu6V+3WhnQFK6+Ezu+e6svd5tTVdCfMexo/i08r6Nf5tW5d+eIS Nxw/fmH8Y20hoZjR7vvVvUPl9/4Od6YtE26dXN2i8dS5teE5v0dfZedL7iksMbqu8b7zOPvj Z7ruF9sZmlpfIXFtqn3kYue9qZuXKLEUZyQaajEXFScCACZ6GRPdAgAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrJIsWRmVeSWpSXmKPExsVy+t9jAd0965YEGJz+ymtxou8Dq8XlXXPY HJg8Pm+SC2CMamC0yUhNTEktUkjNS85PycxLt1XyDo53jjc1MzDUNbS0MFdSyEvMTbVVcvEJ 0HXLzAEaraRQlphTChQKSCwuVtK3wzQhNMRN1wKmMULXNyQIrsfIAA0krGPM+P54P2vBIZ6K RavPsDYwHufsYuTkkBAwkXj18iIzhC0mceHeerYuRi4OIYFFjBInOjcxgSSEBH4xSsy7WA5i swmoSXz5cpgdxBYRMJdYsmgvM0gDs8BXRonGJw1sEA1HGCU2fojvYuTg4BTwlpizhxskLCzg IbH58lewEhYBVYnOky+YQUp4BWwl5r/SBwnzCghK/Jh8jwXEZhbQkli/8zgThC0vsXnNW7By CQF1iUd/dSEuMJI4tPYUI0SJiMS+F+8YJzAKzUIyaRaSSbOQTJqFpGUBI8sqRtHUguSC4qT0 XEO94sTc4tK8dL3k/NxNjOD4fSa1g3Flg8UhRgEORiUeXocfiwOEWBPLiitzDzFKcDArifBG rV0SIMSbklhZlVqUH19UmpNafIjRB+jPicxSosn5wNSSVxJvaGxiZmRpZGZhZGJujkNYSZy3 2SMlQEggPbEkNTs1tSC1CGYcEwenVAPjAn+Lj1MWB02IDCns+DLLfcLHw8zrNukdXxesKJ8d +ecdD6PJxAZ2xghlHTMOwbl5rkotPx52H5GJzLu7sHJ+Wl0bqwbHM7aUJt+jD6uFl+y8V8fg VDFPg7lXYoLZ7rAThU6bdsaq77d+vPzMcgGH59c4DoQ/Yi/bKKB+qnVdrs/b2hNv1ucqsRRn JBpqMRcVJwIAaO3rFQwDAAA= X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, November 15, 2012 3:52 PM Thierry Reding wrote > On Thu, Nov 15, 2012 at 10:30:11AM +0900, Jingoo Han wrote: > > On Friday, November 09, 2012 11:05 PM Thierry Reding wrote > > > > > > 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. > > > > > > Signed-off-by: Thierry Reding > > > > CC'ed Andrew Morton > > Yes, the backlight subsystem isn't very well maintained, so I should > have added Andrew in the first place. Thanks. > > > > > Hi Thierry Reding, > > > > 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 = <&backlight>; > > ... > } > > Then you call something along these lines: > > np = of_parse_phandle(display, "backlight", 0); > if (np) { > backlight = of_find_backlight_by_node(np); > of_node_put(np); > } > > And then use the standard backlight API on the returned pointer. OK, I see how this API can be called. AS you mentioned, it will allow Tegra DRM driver to use the backlight driver. Acked-by: Jingoo Han Best regards, Jingoo Han > > Thierry