From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id E90331B949; Tue, 16 Jan 2024 11:51:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5BD412F4; Tue, 16 Jan 2024 03:52:10 -0800 (PST) Received: from FVFF77S0Q05N (unknown [10.57.90.186]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 50E793F5A1; Tue, 16 Jan 2024 03:51:20 -0800 (PST) Date: Tue, 16 Jan 2024 11:51:14 +0000 From: Mark Rutland To: Stephen Boyd Cc: Rob Herring , linux-kernel@vger.kernel.org, patches@lists.linux.dev, linux-um@lists.infradead.org, linux-arm-kernel@lists.infradead.org, kunit-dev@googlegroups.com, linux-kselftest@vger.kernel.org, devicetree@vger.kernel.org, Frank Rowand , Catalin Marinas , Will Deacon Subject: Re: [PATCH 1/6] arm64: Unconditionally call unflatten_device_tree() Message-ID: References: <20240112200750.4062441-1-sboyd@kernel.org> <20240112200750.4062441-2-sboyd@kernel.org> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240112200750.4062441-2-sboyd@kernel.org> Hi Stephen, On Fri, Jan 12, 2024 at 12:07:44PM -0800, Stephen Boyd wrote: > Call this function unconditionally so that we can populate an empty DTB > on platforms that don't boot with a firmware provided or builtin DTB. > There's no harm in calling unflatten_device_tree() unconditionally. For better or worse, that's not true: there are systems the provide both a DTB *and* ACPI tables, and we must not consume both at the same time as those can clash and cause all sorts of problems. In addition, we don't want people being "clever" and describing disparate portions of their system in ACPI and DT. It is a very deliberate choice to not unflatten the DTB when ACPI is in use, and I don't think we want to reopen this can of worms. Given that, I'm afraid I must NAK this patch. Thanks Mark. > If there isn't a valid initial_boot_params dtb then unflatten_device_tree() > returns early. > > Cc: Rob Herring > Cc: Frank Rowand > Cc: Catalin Marinas > Cc: Will Deacon > Cc: > Signed-off-by: Stephen Boyd > --- > arch/arm64/kernel/setup.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c > index 417a8a86b2db..ede3d59dabf0 100644 > --- a/arch/arm64/kernel/setup.c > +++ b/arch/arm64/kernel/setup.c > @@ -351,8 +351,7 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p) > /* Parse the ACPI tables for possible boot-time configuration */ > acpi_boot_table_init(); > > - if (acpi_disabled) > - unflatten_device_tree(); > + unflatten_device_tree(); > > bootmem_init(); > > -- > https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git/ > https://git.kernel.org/pub/scm/linux/kernel/git/sboyd/spmi.git > >