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=-9.7 required=3.0 tests=BAYES_00,DATE_IN_PAST_03_06, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 3B613C4363A for ; Wed, 28 Oct 2020 22:07:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E47B0246C5 for ; Wed, 28 Oct 2020 22:07:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730133AbgJ1WHc (ORCPT ); Wed, 28 Oct 2020 18:07:32 -0400 Received: from verein.lst.de ([213.95.11.211]:45195 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730063AbgJ1WH2 (ORCPT ); Wed, 28 Oct 2020 18:07:28 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 8D0A568BEB; Wed, 28 Oct 2020 18:22:01 +0100 (CET) Date: Wed, 28 Oct 2020 18:22:01 +0100 From: Christoph Hellwig To: Alexey Kardashevskiy Cc: linuxppc-dev@lists.ozlabs.org, Christoph Hellwig , Michael Ellerman , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH kernel v3 1/2] dma: Allow mixing bypass and mapped DMA operation Message-ID: <20201028172201.GB10015@lst.de> References: <20201028070030.60643-1-aik@ozlabs.ru> <20201028070030.60643-2-aik@ozlabs.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201028070030.60643-2-aik@ozlabs.ru> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 28, 2020 at 06:00:29PM +1100, Alexey Kardashevskiy wrote: > At the moment we allow bypassing DMA ops only when we can do this for > the entire RAM. However there are configs with mixed type memory > where we could still allow bypassing IOMMU in most cases; > POWERPC with persistent memory is one example. > > This adds an arch hook to determine where bypass can still work and > we invoke direct DMA API. The following patch checks the bus limit > on POWERPC to allow or disallow direct mapping. > > This adds a CONFIG_ARCH_HAS_DMA_SET_MASK config option to make arch_xxxx > hooks no-op by default. > > Signed-off-by: Alexey Kardashevskiy > --- > kernel/dma/mapping.c | 24 ++++++++++++++++++++---- > kernel/dma/Kconfig | 4 ++++ > 2 files changed, 24 insertions(+), 4 deletions(-) > > diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c > index 51bb8fa8eb89..a0bc9eb876ed 100644 > --- a/kernel/dma/mapping.c > +++ b/kernel/dma/mapping.c > @@ -137,6 +137,18 @@ static inline bool dma_map_direct(struct device *dev, > return dma_go_direct(dev, *dev->dma_mask, ops); > } > > +#ifdef CONFIG_ARCH_HAS_DMA_MAP_DIRECT > +bool arch_dma_map_page_direct(struct device *dev, phys_addr_t addr); > +bool arch_dma_unmap_page_direct(struct device *dev, dma_addr_t dma_handle); > +bool arch_dma_map_sg_direct(struct device *dev, struct scatterlist *sg, int nents); > +bool arch_dma_unmap_sg_direct(struct device *dev, struct scatterlist *sg, int nents); > +#else > +#define arch_dma_map_page_direct(d, a) (0) > +#define arch_dma_unmap_page_direct(d, a) (0) > +#define arch_dma_map_sg_direct(d, s, n) (0) > +#define arch_dma_unmap_sg_direct(d, s, n) (0) > +#endif A bunch of overly long lines here. Except for that this looks ok to me. If you want me to queue up the series I can just fix it up.