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=-6.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED 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 F065AC43387 for ; Mon, 14 Jan 2019 17:13:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BCA752070B for ; Mon, 14 Jan 2019 17:13:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="E1AjFzik"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="B5HoLqBl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726782AbfANRNe (ORCPT ); Mon, 14 Jan 2019 12:13:34 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:52002 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726643AbfANRNd (ORCPT ); Mon, 14 Jan 2019 12:13:33 -0500 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 6288960851; Mon, 14 Jan 2019 17:13:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1547486012; bh=aRCnqLJEuNYnNcQ1Ed6XhLUR2YS6+c7qQb41LIDJdNg=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=E1AjFzikG7V5pwYoB1f/vwhPl9YXZ6bzONjaQK1uoTKszg5v1T55YJa7Mxya+CQ81 9U02BneeYDdJdUmV1fOJzrvdymSQg1nBEf5lLMFHNpkU5BH7LaVCZ/Kun8vY7IY7Yz EEQbwtfUOjWQuaPHJjW4G8eQqEiT0jVRy9iSbfj4= Received: from lmark-linux.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: lmark@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id E51D5602FC; Mon, 14 Jan 2019 17:13:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1547486011; bh=aRCnqLJEuNYnNcQ1Ed6XhLUR2YS6+c7qQb41LIDJdNg=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=B5HoLqBl1pz5CsbymXctOK+QzpQPUDxTSab+/j6WJCalAY/sXrdOfMb+lW3O87c4F 519KM1iTYoeRpftEWFQGG+kZK7n6LPmdxv8bqwO50VoL3Pcn4iiAbVumDPHNKQeVYv E0CRhDHY0AGCQD8z5Hp9CfwWdmjCBq19j16PjlQ4= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org E51D5602FC Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=lmark@codeaurora.org Date: Mon, 14 Jan 2019 09:13:30 -0800 (PST) From: Liam Mark X-X-Sender: lmark@lmark-linux.qualcomm.com To: "Andrew F. Davis" cc: Laura Abbott , Sumit Semwal , Greg Kroah-Hartman , =?ISO-8859-15?Q?Arve_Hj=F8nnev=E5g?= , devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: Re: [PATCH 13/14] staging: android: ion: Do not sync CPU cache on map/unmap In-Reply-To: <20190111180523.27862-14-afd@ti.com> Message-ID: References: <20190111180523.27862-1-afd@ti.com> <20190111180523.27862-14-afd@ti.com> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 11 Jan 2019, Andrew F. Davis wrote: > Buffers may not be mapped from the CPU so skip cache maintenance here. > Accesses from the CPU to a cached heap should be bracketed with > {begin,end}_cpu_access calls so maintenance should not be needed anyway. > > Signed-off-by: Andrew F. Davis > --- > drivers/staging/android/ion/ion.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c > index 14e48f6eb734..09cb5a8e2b09 100644 > --- a/drivers/staging/android/ion/ion.c > +++ b/drivers/staging/android/ion/ion.c > @@ -261,8 +261,8 @@ static struct sg_table *ion_map_dma_buf(struct dma_buf_attachment *attachment, > > table = a->table; > > - if (!dma_map_sg(attachment->dev, table->sgl, table->nents, > - direction)) > + if (!dma_map_sg_attrs(attachment->dev, table->sgl, table->nents, > + direction, DMA_ATTR_SKIP_CPU_SYNC)) Unfortunately I don't think you can do this for a couple reasons. You can't rely on {begin,end}_cpu_access calls to do cache maintenance. If the calls to {begin,end}_cpu_access were made before the call to dma_buf_attach then there won't have been a device attached so the calls to {begin,end}_cpu_access won't have done any cache maintenance. Also ION no longer provides DMA ready memory, so if you are not doing CPU access then there is no requirement (that I am aware of) for you to call {begin,end}_cpu_access before passing the buffer to the device and if this buffer is cached and your device is not IO-coherent then the cache maintenance in ion_map_dma_buf and ion_unmap_dma_buf is required. > return ERR_PTR(-ENOMEM); > > return table; > @@ -272,7 +272,8 @@ static void ion_unmap_dma_buf(struct dma_buf_attachment *attachment, > struct sg_table *table, > enum dma_data_direction direction) > { > - dma_unmap_sg(attachment->dev, table->sgl, table->nents, direction); > + dma_unmap_sg_attrs(attachment->dev, table->sgl, table->nents, > + direction, DMA_ATTR_SKIP_CPU_SYNC); > } > > static int ion_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma) > -- > 2.19.1 > > _______________________________________________ > devel mailing list > devel@linuxdriverproject.org > http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project