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 5D531286B6; Thu, 18 Jan 2024 15:26:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705591613; cv=none; b=pJzADmVstUGnDcNm6ULIS63EV7oYUA0X1kUX7qPZSBqgtdUaO+I7IJGEQIJcIA6CvXQ0LxuIbPFESzecKUkJYPrXMNrCUJj25VHgkOI0a15hUPXPEq1kRMIVuzjKA5dmx8gAeSkB1cxBvqk7lhPf1R93OY0N+jUI3kcWXwZXQUM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705591613; c=relaxed/simple; bh=fu6GheHEBNxmSs1bBTsooD1uUVG41pw1PIGUREayObY=; h=Received:Received:Date:From:To:Cc:Subject:Message-ID:References: MIME-Version:Content-Type:Content-Disposition:In-Reply-To; b=RU/9W63JUOsqX8G0g9BPfhmMhBewZeXiLijzERJ2NfjTKM4DNUUqdY/SG9J+OjTfD1sDyPx0wf9f6ZLtlfIcQWGXAC/Op3AK3KTL4v9c5WK18cZB8UXoUJNXKonTdXwiH8WS1jqZaybl78yrmWsWFmWlPdO8kjfb03wXGtby4Jg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 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 2A8C11042; Thu, 18 Jan 2024 07:27:36 -0800 (PST) Received: from FVFF77S0Q05N.cambridge.arm.com (FVFF77S0Q05N.cambridge.arm.com [10.1.28.174]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 73C1F3F73F; Thu, 18 Jan 2024 07:26:47 -0800 (PST) Date: Thu, 18 Jan 2024 15:26:43 +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> <434b21afe1899b1567f3617261594842.sboyd@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@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: <434b21afe1899b1567f3617261594842.sboyd@kernel.org> On Tue, Jan 16, 2024 at 05:27:18PM -0800, Stephen Boyd wrote: > Quoting Mark Rutland (2024-01-16 03:51:14) > > 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. > > Hmm ok. I missed this part. Can we knock out the initial_boot_params in > this case so that we don't unflatten a DTB when ACPI is in use? Why is that better than just not calling unflatten_device_tree(), as we do today? The cover letter says this is all so that we can run DT tests for the clk framework; why can't that just depend on the system being booted with DT rather than ACPI? We have other tests which are architecture and/or configuration dependent... Mark.