From patchwork Sat Dec 26 03:35:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: chenzhou X-Patchwork-Id: 11990243 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,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,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 00A70C433DB for ; Sat, 26 Dec 2020 03:31:35 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B33C520897 for ; Sat, 26 Dec 2020 03:31:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B33C520897 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-ID:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=FVljxmgoUmaKMUVrqZaGhnfnbCmlEx8CsZ3Fd1ngGVk=; b=QI2Y4YOM8oVNZJT2jdt02HbM+ RUD/vqmTtlLaoSx/xugLgfBinJ8rvJubUH0swJPZyFxRol6N5KKYzicstH9DEX1XYAtLKyYAnVSv+ zc0flnLXmta8DmOg9NI1xXo3CdfaWbwjLvQpLL8HQZ+2hYbm+YTF4YAYsGOd4wMepdtuD0PgMGJ9J gli2lAnimLdpiwpOMJH2wC/OK4p7PT8HuH3LefgiEQKNz8Ss7bhq5l8jI/AMFbxjk6bUYXt73kjiW e/YiIwEZAXRh0TRuW3wiWYE4cVLlZzRfYpxtehlwJKhROYzNCkb/WUo0cz/bMcHV1dkLLCWvvkQnv 7n9EYsaMQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kt0HD-0002Lc-FR; Sat, 26 Dec 2020 03:29:55 +0000 Received: from szxga06-in.huawei.com ([45.249.212.32]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kt0H6-0002Jd-I9 for linux-arm-kernel@lists.infradead.org; Sat, 26 Dec 2020 03:29:49 +0000 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.60]) by szxga06-in.huawei.com (SkyGuard) with ESMTP id 4D2q6N0rPzzhxS7; Sat, 26 Dec 2020 11:29:00 +0800 (CST) Received: from localhost.localdomain.localdomain (10.175.113.25) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.498.0; Sat, 26 Dec 2020 11:29:27 +0800 From: Chen Zhou To: , Subject: [PATCH 1/2] arm64: mm: update the comments about ZONE_DMA Date: Sat, 26 Dec 2020 11:35:56 +0800 Message-ID: <20201226033557.116251-2-chenzhou10@huawei.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20201226033557.116251-1-chenzhou10@huawei.com> References: <20201226033557.116251-1-chenzhou10@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.113.25] X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201225_222948_920794_C70DC7FB X-CRM114-Status: UNSURE ( 9.17 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: song.bao.hua@hisilicon.com, xiexiuqi@huawei.com, chenzhou10@huawei.com, linux-kernel@vger.kernel.org, rppt@kernel.org, huawei.libin@huawei.com, akpm@linux-foundation.org, ardb@kernel.org, nsaenzjulienne@suse.de, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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;