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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 32E71C4363D for ; Tue, 22 Sep 2020 13:39:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AD6DD20936 for ; Tue, 22 Sep 2020 13:39:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Qcrd+4KU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726807AbgIVNjo (ORCPT ); Tue, 22 Sep 2020 09:39:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58296 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726778AbgIVNjn (ORCPT ); Tue, 22 Sep 2020 09:39:43 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 29AAAC0613D1 for ; Tue, 22 Sep 2020 06:39:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=Dj0SE+agkMPt4RtgGrQDspMH2G8cNUOwicknqNk5yZA=; b=Qcrd+4KUpPW6lmO0FyhIU3+sBa wcNoL5YDdT1H4u8iBEIvwmObNtIoR1ZviLjJ8tXgpCye/WihOtGde4DhWNMNxHD13FMMAXE0sTTcZ auTQJKt3wq7plJ23hsuk5XTAR7DxcrqEjSVgG1xP9d7CTRWmaPQ5GiskA31NGC3ivN0ul1ceZ7OOH Fo+fEFx4PkPZihLWHcNDXtta+Od+ryR7qYyhKdFZEjl9QWZSvHg1fCjidzuZd6I+CPZwj8EjvfPMm dM7f57AEH6xyO0u1pgXUo5w9NFqN9iU5kP5TijIPzv/fT6fNXx8NMtHVWZxWwNm9MhQOm6vbF4KSN O1SgBZdg==; Received: from p4fdb0c34.dip0.t-ipconnect.de ([79.219.12.52] helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kKiWC-0005MM-RC; Tue, 22 Sep 2020 13:39:41 +0000 From: Christoph Hellwig To: iommu@lists.linux-foundation.org Cc: Dominik Brodowski , linux-kernel@vger.kernel.org Subject: [PATCH 3/3] dma-mapping: better document dma_addr_t and DMA_MAPPING_ERROR Date: Tue, 22 Sep 2020 15:40:02 +0200 Message-Id: <20200922134002.1227279-4-hch@lst.de> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200922134002.1227279-1-hch@lst.de> References: <20200922134002.1227279-1-hch@lst.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Move the comment documenting dma_addr_t away from the dma_map_ops definition which isn't very related to it, and toward DMA_MAPPING_ERROR, which is somewhat related. Add a little blurb about DMA_MAPPING_ERROR as well. Signed-off-by: Christoph Hellwig --- include/linux/dma-mapping.h | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 51e93d44b826c8..c4395cf7e265dd 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -67,12 +67,6 @@ */ #define DMA_ATTR_PRIVILEGED (1UL << 9) -/* - * A dma_addr_t can hold any valid DMA or bus address for the platform. - * It can be given to a device to use as a DMA source or target. A CPU cannot - * reference a dma_addr_t directly because there may be translation between - * its physical address space and the bus address space. - */ struct dma_map_ops { void* (*alloc)(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t gfp, @@ -131,6 +125,16 @@ struct dma_map_ops { unsigned long (*get_merge_boundary)(struct device *dev); }; +/* + * A dma_addr_t can hold any valid DMA or bus address for the platform. It can + * be given to a device to use as a DMA source or target. A CPU cannot + * reference a dma_addr_t directly because there may be translation between its + * physical address space and the bus address space. + * + * DMA_MAPPING_ERROR is the magic error code if a mapping failed. It should not + * be used directly in drivers, but checked for using dma_mapping_error() + * instead. + */ #define DMA_MAPPING_ERROR (~(dma_addr_t)0) extern const struct dma_map_ops dma_virt_ops; -- 2.28.0