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=-6.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, 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 87634C433E0 for ; Thu, 11 Feb 2021 09:15:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4E31F60230 for ; Thu, 11 Feb 2021 09:15:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229564AbhBKJPV (ORCPT ); Thu, 11 Feb 2021 04:15:21 -0500 Received: from mail.kernel.org ([198.145.29.99]:40864 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229705AbhBKJDi (ORCPT ); Thu, 11 Feb 2021 04:03:38 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id EDD6364E08; Thu, 11 Feb 2021 09:02:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1613034166; bh=toje9XjA7hPGFbcvbm2+Hg56n6gVz61TA+aTOG90wPo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KQh3C5C8LzqHHJCJOXB99OdAeD5xdCmCISLGyGV180RrzZrsKQcguY8rfJf22ywNU C39UXGJ/JvNBJ/wQArfs3Fra4oJNgrahaFVUq1IIBGzt0HOklnGKNWSG8xo8iX6Zq1 Xq7iRh1B0Zz8YJfmOtq1xaQyyiB5/CZ1Qvxlw0OE= Date: Thu, 11 Feb 2021 10:02:42 +0100 From: Greg Kroah-Hartman To: Noam Liron Cc: "linux-usb@vger.kernel.org" , Yuval Shaia Subject: Re: [EXT] Re: Enforce USB DMA allocations to specific range Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org A: http://en.wikipedia.org/wiki/Top_post Q: Were do I find info about this thing called top-posting? A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail? A: No. Q: Should I include quotations after my reply? http://daringfireball.net/2007/07/on_top On Thu, Feb 11, 2021 at 08:38:40AM +0000, Noam Liron wrote: > Hi Greg, > > I am writing you again on the below subject, as I would like to get a > "high level" opinion, and you are probably the most experienced ... I am not a DMA expert at all, why not ask the dma developers instead? > As I wrote below, I cannot rely on the DMA mask, as some USB > allocation are not affected by it. Why "some" and not "others"? Perhaps you need to fix your platform code to prevent that from happening instead? Why is USB unique here? > I thought of using private DMA pool that will be allocated where I > need it (at the start of physical memory). However, this means adding > specific ASIC code, which is less elegant. > Do you think that's the right way? I do not know your platform, only you do. But I do think you should not be doing new development on 4.14, as that is a very old and obsolete kernel and the dma code in the kernel has changed a lot since 2017. good luck! greg k-h