From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Frias Subject: Re: ARM, SoC: About the use DT-defined properties by 3rd-party drivers Date: Mon, 12 Sep 2016 18:29:06 +0200 Message-ID: <57D6D7D2.7030507@laposte.net> References: <57BDAF2E.10502@laposte.net> <57D69FB1.2020801@laposte.net> <20160912123809.GB13741@leverpostej> <57D6AA54.6000208@laposte.net> <20160912135549.GA14165@leverpostej> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Warner Losh , Mark Rutland Cc: devicetree , Mason , Timur Tabi , Linux ARM , LKML List-Id: devicetree@vger.kernel.org Hi Warner, On 09/12/2016 04:26 PM, Warner Losh wrote: > On Mon, Sep 12, 2016 at 8:01 AM, Mark Rutland wrote: >>> Since the question seems understood, do you have an example of other SoC's >>> doing something similar? >> >> I do not have an example. I know that others are using DT for data >> beyond what Linux or another OS requires, but it's my understanding that >> that is typically in a separate DTB. > > Just to clarify: FreeBSD uses, for the most part, the DTB's that the > 'vendor' ships, which is quite often the same ones included in Linux. > There's some exceptions where the bindings weren't really hardware > independent, or where the abstraction model was really Linux specific > (for things like the HDMI stack). > > However, with the advent of overlays, one would think that a vendor > could easily include an overlay with the DTB data for the devices they > don't wish to, or cannot for other reasons release. It seems like the > perfect mechanism to comply with the rules about inclusion of nodes in > the DTS. Vendors are free to document these nodes and don't require > the Linux kernel include them in the Documents directory to do so. > There have been recent efforts to move this documentation to a third > party to maintain. This is very interesting, do you have a more concrete example of such usage? The overlay technique could be a solution, but so is forking and distributing a non-documented DT. That's why I'd put this solution a little bit lower than just exposing the entire HW description through the DT. Best regards, Sebastian