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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 91C38C433E0 for ; Wed, 30 Dec 2020 10:18:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B16922227 for ; Wed, 30 Dec 2020 10:18:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726525AbgL3KR4 (ORCPT ); Wed, 30 Dec 2020 05:17:56 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:9661 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726247AbgL3KRz (ORCPT ); Wed, 30 Dec 2020 05:17:55 -0500 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4D5Ryb5s2Xz15kbL; Wed, 30 Dec 2020 18:16:23 +0800 (CST) Received: from localhost.localdomain.localdomain (10.175.113.25) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.498.0; Wed, 30 Dec 2020 18:17:03 +0800 From: Chen Zhou To: , CC: , , , , , , , , Subject: [PATCH v2 1/3] arm64: mm: update the comments about ZONE_DMA Date: Wed, 30 Dec 2020 18:23:20 +0800 Message-ID: <20201230102322.176313-2-chenzhou10@huawei.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20201230102322.176313-1-chenzhou10@huawei.com> References: <20201230102322.176313-1-chenzhou10@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.175.113.25] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since patchset "arm64: Default to 32-bit wide ZONE_DMA", ZONE_DMA's size is fine-tuned. In the absence of addressing limited masters, ZONE_DMA will span the whole 32-bit address space, otherwise, in the case of the Raspberry Pi 4, it'll only span the 30-bit address space. Update the comments. Signed-off-by: Chen Zhou Reviewed-by: Nicolas Saenz Julienne --- arch/arm64/mm/init.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 75addb36354a..7b9809e39927 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -53,10 +53,11 @@ s64 memstart_addr __ro_after_init = -1; EXPORT_SYMBOL(memstart_addr); /* - * We create both ZONE_DMA and ZONE_DMA32. ZONE_DMA covers the first 1G of - * memory as some devices, namely the Raspberry Pi 4, have peripherals with - * this limited view of the memory. ZONE_DMA32 will cover the rest of the 32 - * bit addressable memory area. + * We create both ZONE_DMA and ZONE_DMA32. ZONE_DMA's size is fine-tuned. + * In the absence of addressing limited masters, ZONE_DMA will span the + * whole 32-bit address space, otherwise, in the case of the Raspberry Pi 4, + * it'll only span the 30-bit address space. ZONE_DMA32 will cover the rest + * of the 32 bit addressable memory area. */ phys_addr_t arm64_dma_phys_limit __ro_after_init; static phys_addr_t arm64_dma32_phys_limit __ro_after_init; -- 2.20.1