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 X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0D1D5C4727E for ; Thu, 1 Oct 2020 17:19:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C69DC20872 for ; Thu, 1 Oct 2020 17:19:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732287AbgJART1 (ORCPT ); Thu, 1 Oct 2020 13:19:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:49304 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732213AbgJART1 (ORCPT ); Thu, 1 Oct 2020 13:19:27 -0400 Received: from gaia (unknown [31.124.44.166]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 069D92085B; Thu, 1 Oct 2020 17:19:24 +0000 (UTC) Date: Thu, 1 Oct 2020 18:19:22 +0100 From: Catalin Marinas To: Nicolas Saenz Julienne Cc: robh+dt@kernel.org, hch@lst.de, robin.murphy@arm.com, devicetree@vger.kernel.org, iommu@lists.linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, will@kernel.org, linux-arm-kernel@lists.infradead.org, linux-rpi-kernel@lists.infradead.org Subject: Re: [PATCH 3/4] arm64: Default to 32-bit ZONE_DMA Message-ID: <20201001171922.GO21544@gaia> References: <20201001161740.29064-1-nsaenzjulienne@suse.de> <20201001161740.29064-4-nsaenzjulienne@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201001161740.29064-4-nsaenzjulienne@suse.de> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Thu, Oct 01, 2020 at 06:17:39PM +0200, Nicolas Saenz Julienne wrote: > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index e1a69a618832..3c3f462466eb 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -43,8 +43,6 @@ > #include > #include > > -#define ARM64_ZONE_DMA_BITS 30 > - > /* > * We need to be able to catch inadvertent references to memstart_addr > * that occur (potentially in generic code) before arm64_memblock_init() > @@ -388,8 +386,14 @@ void __init arm64_memblock_init(void) > early_init_fdt_scan_reserved_mem(); > > if (IS_ENABLED(CONFIG_ZONE_DMA)) { > - zone_dma_bits = ARM64_ZONE_DMA_BITS; > - arm64_dma_phys_limit = max_zone_phys(ARM64_ZONE_DMA_BITS); > + /* > + * early_init_dt_scan() might alter zone_dma_bits based on the > + * device's DT. Otherwise, have it cover the 32-bit address > + * space. > + */ > + if (zone_dma_bits == ZONE_DMA_BITS_DEFAULT) > + zone_dma_bits = 32; > + arm64_dma_phys_limit = max_zone_phys(zone_dma_bits); So here we assume that if zone_dma_bits is 24, it wasn't initialised. I think it may be simpler if we just set it in setup_machine_fdt() to 32 or 30 if RPi4. This way we don't have to depend on what the core kernel sets. -- Catalin