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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 EBE02C433FF for ; Tue, 30 Jul 2019 13:43:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CD711206B8 for ; Tue, 30 Jul 2019 13:43:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731225AbfG3Nnj (ORCPT ); Tue, 30 Jul 2019 09:43:39 -0400 Received: from mail-qt1-f194.google.com ([209.85.160.194]:45241 "EHLO mail-qt1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725793AbfG3Nni (ORCPT ); Tue, 30 Jul 2019 09:43:38 -0400 Received: by mail-qt1-f194.google.com with SMTP id x22so58110265qtp.12; Tue, 30 Jul 2019 06:43:37 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=HUMgES4eSdx7Gb1wHf4vgNUcT1viL6l/JJUreDv7DAI=; b=rvgYy2Z0k649zlfGfNIVsM/rbnnF6m3wP1uGvhhhuDcf8C0DW014P0oGFSAfJWaHxR DREOPuw6Ow6640D3q4IUeohjLMGw0R0OU2QNfvRD8ovgvaMcCCzUnlRhILWarpsQSs1n 8FUib1Iu+8Vbbyou77raJqQbcHcEBR6JufQlmabd0PF7tQErv2ecT9DUbWQsMtCU8nDB KgDMdVWA5BrNB2xnEBAmEmBmojXs+icMAKYq1W6c3KVgzHjJcH0NtiTV5ardV1rI4L4E 3CD+b5vlueGnN/JzUu+xPj7J6MVBlOCVo2pWi1gmnEebN/ERh48ayO7Zoy0XaLZO31sP WZMw== X-Gm-Message-State: APjAAAVuUf77BZ77JAjX9/CleFtVULpFHCxa627p1LKRMgE47RAc6Ssq AAaScmiazxls44yg7wSYV8IGmtvpnI/dStM8tCs= X-Google-Smtp-Source: APXvYqzk4myI3khjNxlQnHaI9ZcgvMI5FOmQpZ2ORwmh2H4e5fyHlvNQY96ZcLDUkT4i2hDktBvBnnKAR3H1vEsYzAU= X-Received: by 2002:ac8:f99:: with SMTP id b25mr73930879qtk.142.1564494217063; Tue, 30 Jul 2019 06:43:37 -0700 (PDT) MIME-Version: 1.0 References: <1564488945-20149-1-git-send-email-guoren@kernel.org> <1564488945-20149-4-git-send-email-guoren@kernel.org> In-Reply-To: <1564488945-20149-4-git-send-email-guoren@kernel.org> From: Arnd Bergmann Date: Tue, 30 Jul 2019 15:43:20 +0200 Message-ID: Subject: Re: [PATCH 4/4] csky: Add dma_inv_range for DMA_FROM_DEVICE To: Guo Ren Cc: Linux Kernel Mailing List , linux-arch , linux-csky@vger.kernel.org, feng_shizhu@dahuatech.com, zhang_jian5@dahuatech.com, zheng_xingjian@dahuatech.com, zhu_peng@dahuatech.com, Guo Ren Content-Type: text/plain; charset="UTF-8" Sender: linux-csky-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-csky@vger.kernel.org On Tue, Jul 30, 2019 at 2:16 PM wrote: > From: Guo Ren > diff --git a/arch/csky/mm/dma-mapping.c b/arch/csky/mm/dma-mapping.c > index 3f1ff9d..d8f0f81 100644 > --- a/arch/csky/mm/dma-mapping.c > +++ b/arch/csky/mm/dma-mapping.c > @@ -72,6 +72,8 @@ void arch_sync_dma_for_device(struct device *dev, phys_addr_t paddr, > cache_op(paddr, size, dma_wb_range); > break; > case DMA_FROM_DEVICE: > + cache_op(paddr, size, dma_inv_range); > + break; > case DMA_BIDIRECTIONAL: > cache_op(paddr, size, dma_wbinv_range); > break; > @@ -88,6 +90,8 @@ void arch_sync_dma_for_cpu(struct device *dev, phys_addr_t paddr, > cache_op(paddr, size, dma_wb_range); > break; > case DMA_FROM_DEVICE: > + cache_op(paddr, size, dma_inv_range); > + break; > case DMA_BIDIRECTIONAL: > cache_op(paddr, size, dma_wbinv_range); > break; When syncing 'for_cpu', you should not need to write back, because there won't be any dirty cache lines. If you have a CPU core that does not do speculative loads, you also don't need to invalidate here, because you have already done that in the _for_device() case, the only reason to invalidate the CPU cache again is if a speculative load created a stale cache line that now shadows the data received from the device. Arnd