From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3B318C43334 for ; Fri, 24 Jun 2022 12:05:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229635AbiFXMFO (ORCPT ); Fri, 24 Jun 2022 08:05:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53930 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229615AbiFXMFO (ORCPT ); Fri, 24 Jun 2022 08:05:14 -0400 Received: from relay8-d.mail.gandi.net (relay8-d.mail.gandi.net [IPv6:2001:4b98:dc4:8::228]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2E5917E008; Fri, 24 Jun 2022 05:05:10 -0700 (PDT) Received: (Authenticated sender: clement.leger@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id 996271BF206; Fri, 24 Jun 2022 12:05:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1656072308; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=NtimK2j9hjJLarYb6jxp0BccsheWgcp8ThrrZdPqS0o=; b=lt6EZbzuYv4GcSMuTExbY1eY89PGvcNJc6+vh5TlzmLPI8POGBDxBsUHEjPiBRtsJCHbP6 jwwgLHJA92XZFsUGodAMK05CQupmO86ogKIAs2lh/oJag4dNkoYexbDM4YPuLXnF2gtdKN hhIGz/AQlbD/sin5T0EdNj70t9wYUAfy0Uspl5HqXPGYqXcjx93qhcoKikhumys8+cSZyS /gsDLEkE/pZaQ/oSM/m4gnoHHEHapNbOALYVIWS3ufUcptiAVvMu4PqPfxI7mJLcHB5ZZ4 8TqJx4ESolKJpK0pwDCxg5i4jiarIqepHL2UkvHGr0L+BMAgg4ARmBxOcey5bg== Date: Fri, 24 Jun 2022 14:04:15 +0200 From: =?UTF-8?B?Q2zDqW1lbnQgTMOpZ2Vy?= To: Frank Rowand Cc: Rob Herring , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Lizhi Hou , Allan Nielsen , Horatiu Vultur , Steen Hegelund , Thomas Petazzoni , Rob Herring Subject: Re: [PATCH v1 1/2] of: base: populate of_root node if not set Message-ID: <20220624140415.677a12c1@fixe.home> In-Reply-To: References: <20220623105044.152832-1-clement.leger@bootlin.com> <20220623105044.152832-2-clement.leger@bootlin.com> Organization: Bootlin X-Mailer: Claws Mail 4.1.0 (GTK 3.24.34; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Le Thu, 23 Jun 2022 18:15:31 -0500, Frank Rowand a =C3=A9crit : > Hi Clement, >=20 > I said that I would send a patch to do this, but have failed to follow > through. Sorry about that. Hi Frank, no worries, I just needed this topic to move forward, that's why I decided to sent this . Thanks ! Cl=C3=A9ment >=20 >=20 > On 6/23/22 06:50, Cl=C3=A9ment L=C3=A9ger wrote: > > When enabling CONFIG_OF on a platform where of_root is not populated by > > firmware, we end up without a root node. In order to apply overlays and > > create subnodes of the root node, we need one. Create this root node > > by unflattening an empty builtin dtb with of_fdt_unflatten(). > >=20 > > Co-developed-by: Rob Herring > > Signed-off-by: Rob Herring > > Signed-off-by: Cl=C3=A9ment L=C3=A9ger > > --- > > drivers/of/Makefile | 2 +- > > drivers/of/base.c | 18 ++++++++++++++++-- > > drivers/of/empty_root.dts | 6 ++++++ > > 3 files changed, 23 insertions(+), 3 deletions(-) > > create mode 100644 drivers/of/empty_root.dts > >=20 > > diff --git a/drivers/of/Makefile b/drivers/of/Makefile > > index e0360a44306e..ce56c8b95c83 100644 > > --- a/drivers/of/Makefile > > +++ b/drivers/of/Makefile > > @@ -1,5 +1,5 @@ > > # SPDX-License-Identifier: GPL-2.0 > > -obj-y =3D base.o device.o platform.o property.o > > +obj-y =3D base.o empty_root.dtb.o device.o platform.o property.o > > obj-$(CONFIG_OF_KOBJ) +=3D kobj.o > > obj-$(CONFIG_OF_DYNAMIC) +=3D dynamic.o > > obj-$(CONFIG_OF_FLATTREE) +=3D fdt.o > > diff --git a/drivers/of/base.c b/drivers/of/base.c > > index d4f98c8469ed..43e0f027a49c 100644 > > --- a/drivers/of/base.c > > +++ b/drivers/of/base.c > > @@ -22,6 +22,7 @@ > > #include > > #include > > #include > > +#include > > #include > > #include > > #include > > @@ -163,6 +164,8 @@ void __of_phandle_cache_inv_entry(phandle handle) > > phandle_cache[handle_hash] =3D NULL; > > } > > =20 > > +extern const char __dtb_empty_root_begin[]; > > + > > void __init of_core_init(void) > > { > > struct device_node *np; > > @@ -176,6 +179,18 @@ void __init of_core_init(void) > > pr_err("failed to register existing nodes\n"); > > return; > > } > > + > > + if (!of_root) { > > + void *dt; > > + const unsigned long *fdt =3D (const unsigned long *) > > + __dtb_empty_root_begin; > > + dt =3D of_fdt_unflatten_tree(fdt, NULL, &of_root); > > + if (!dt) { > > + pr_err("Failed to setup empty root dt\n"); > > + return; > > + } > > + } > > + > > for_each_of_allnodes(np) { > > __of_attach_node_sysfs(np); > > if (np->phandle && !phandle_cache[of_phandle_cache_hash(np->phandle)= ]) > > @@ -184,8 +199,7 @@ void __init of_core_init(void) > > mutex_unlock(&of_mutex); > > =20 > > /* Symlink in /proc as required by userspace ABI */ > > - if (of_root) > > - proc_symlink("device-tree", NULL, "/sys/firmware/devicetree/base"); > > + proc_symlink("device-tree", NULL, "/sys/firmware/devicetree/base"); > > } =20 >=20 > This approach is adding an additional method of unflattening the tree. > I would prefer to consolidate in a single location. >=20 > I have leveraged this patch series into a different patch series to > accomplish that. I have boot tested with one configuration, but want > to test two more configurations before sending the new series. It > should only take "a few minutes". >=20 > -Frank >=20 > > =20 > > static struct property *__of_find_property(const struct device_node *n= p, > > diff --git a/drivers/of/empty_root.dts b/drivers/of/empty_root.dts > > new file mode 100644 > > index 000000000000..cf9e97a60f48 > > --- /dev/null > > +++ b/drivers/of/empty_root.dts > > @@ -0,0 +1,6 @@ > > +// SPDX-License-Identifier: GPL-2.0-only > > +/dts-v1/; > > + > > +/ { > > + > > +}; =20 >=20 --=20 Cl=C3=A9ment L=C3=A9ger, Embedded Linux and Kernel engineer at Bootlin https://bootlin.com