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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 B3344C0650F for ; Mon, 5 Aug 2019 15:17:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7CB1E21734 for ; Mon, 5 Aug 2019 15:17:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565018237; bh=x10plgI7L0b67A1k2vgybhQdDfioCS+r/a9+H4Zcftk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=x+o3lgy/5g1JoWxldwnOd8paOEoQK7kdLrlX2xns6SaRYNI3ktzT86ziizT+wzUVV QZw24krKgjTQ6JnflEn9hAopPbi/Qt+sN12kdTG71oabU7dG+kgOTftKVWSBMMY/VY YX130F5MC4nc8RwcSeUXMnxVXoTl7kqBOQRjlxDE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728933AbfHEPRQ (ORCPT ); Mon, 5 Aug 2019 11:17:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:39238 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728468AbfHEPRQ (ORCPT ); Mon, 5 Aug 2019 11:17:16 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6256F216F4; Mon, 5 Aug 2019 15:17:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565018235; bh=x10plgI7L0b67A1k2vgybhQdDfioCS+r/a9+H4Zcftk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=uVtd7O8Yh7gmgrzaZiZTH1TZ/7VIb9NMu71+EnqCeO8Znhq4zHb+pwNplgT1u39uR B+asBF8sXj5keDWeEUuChAjzXbhd5nlfLaQY3UqP4vGokJJ5rR89JSeX02o+vQRmKP bS6PTFyE8Va1ubvPY509Nvo+B+6nfQ2N+rDrRwqo= Date: Mon, 5 Aug 2019 17:17:13 +0200 From: Greg KH To: Gavin Li Cc: linux-usb@vger.kernel.org, Gavin Li Subject: Re: [PATCH] usb: devio: fix mmap() on non-coherent DMA architectures Message-ID: <20190805151713.GA7067@kroah.com> References: <20190801220436.3871-1-gavinli@thegavinli.com> <20190802121416.GA20689@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Fri, Aug 02, 2019 at 10:57:00AM -0700, Gavin Li wrote: > usbfs mmap() looks like it was introduced for 4.6 in commit > f7d34b445abc, so it should probably be backported to 4.9 and onwards. > This issue has been present since the introduction of the feature. > > One sidenote: this patch will cause the following warning on x86 due > to dmap_mmap_coherent() trying to map normal memory in as uncached: > > x86/PAT: ... map pfn RAM range req uncached-minus for [mem > 0x77b000000-0x77b210fff], got write-back > > This warning is harmless, as x86 is DMA coherent and the memory gets > correctly mapped in as write-back. I will submit a patch to the DMA > mapping team to eliminate this warning. Let me know what the git commit id of that patch is, I will wait for it to hit the tree before adding this one. thanks, greg k-h