From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jacek Anaszewski Subject: Re: [PATCH v2 2/2] leds/powernv: Add driver for PowerNV platform Date: Fri, 24 Apr 2015 12:16:29 +0200 Message-ID: <20150424121629.69a159b3@ja.home> References: <20150422234509.626d9dc7@ja.home> <55388254.4000606@linux.vnet.ibm.com> <20150423161342.55e9ac8f@ja.home> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from mail-wi0-f177.google.com ([209.85.212.177]:37391 "EHLO mail-wi0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752668AbbDXKQi (ORCPT ); Fri, 24 Apr 2015 06:16:38 -0400 Received: by widdi4 with SMTP id di4so14779698wid.0 for ; Fri, 24 Apr 2015 03:16:37 -0700 (PDT) In-Reply-To: Sender: linux-leds-owner@vger.kernel.org List-Id: linux-leds@vger.kernel.org To: Stewart Smith Cc: linux-leds@vger.kernel.org, cooloney@gmail.com, rpurdie@rpsys.net, linuxppc-dev@lists.ozlabs.org, khandual@linux.vnet.ibm.com On Fri, 24 Apr 2015 14:18:30 +1000 Stewart Smith wrote: > Jacek Anaszewski writes: > >> These device tree comes from out firmware ... which is immutable . > > > > How the firmware is related to kernel? These bindings are for > > kernel, not for the firmware. > > > > DT bindings are compiled to *.dtb file which is concatenated with > > zImage. During system boot device drivers are matched with DT > > bindings through 'compatible' property. A driver should have single > > matching DT node, i.e. no other driver can probe with the same DT > > node. This implies that the node should contain only the properties > > required for configuring the related device. > > For OPAL firmware on POWER, firmware hands kernel a flattened device > tree of the machine it's booting on. It's not added to kernel as the > kernels aren't board specific - they're generic. Is the DT node we are discussing used by some other drivers than the LED class driver? Or is it required in this form by other components of your platform? > https://github.com/open-power/skiboot/ is the firmware that generates > the device tree for booting under OPAL. > -- Best Regards, Jacek Anaszewski