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 76D18C433E0 for ; Tue, 9 Feb 2021 09:28:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 443CF64E16 for ; Tue, 9 Feb 2021 09:28:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229707AbhBIJ2I (ORCPT ); Tue, 9 Feb 2021 04:28:08 -0500 Received: from mail.kernel.org ([198.145.29.99]:51556 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229770AbhBIJXz (ORCPT ); Tue, 9 Feb 2021 04:23:55 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id BF67C64E4F; Tue, 9 Feb 2021 09:23:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1612862595; bh=ZuzO8IlPH7OdvzOuM3hUuPGrV2BGw7BR18s5NWN+cQo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=2IZd9JV5qM4aI8JsCkjZZuIE+UcwO+cZ/8Tzp/xkBac6h1v5ahUFGgLchn6WAvHWP TTpbmG95sCUDlWRidU6dAfH5GDSinRQmdtdG5VZuur1DwcnrvtroT/g4T4IlgJjrY5 7e9KljC+q9VAdsCIo/5dP1dy/Ykm0EgIhSJoAfSo= Date: Tue, 9 Feb 2021 10:23:12 +0100 From: Greg KH To: obayashi.yoshimasa@socionext.com Cc: sumit.garg@linaro.org, hch@lst.de, m.szyprowski@samsung.com, robin.murphy@arm.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, daniel.thompson@linaro.org Subject: Re: DMA direct mapping fix for 5.4 and earlier stable branches Message-ID: References: <27bbe35deacb4ca49f31307f4ed551b5@SOC-EX02V.e01.socionext.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <27bbe35deacb4ca49f31307f4ed551b5@SOC-EX02V.e01.socionext.com> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Tue, Feb 09, 2021 at 09:05:40AM +0000, obayashi.yoshimasa@socionext.com wrote: > > > As the drivers are currently under development and Socionext has > > > chosen 5.4 stable kernel for their development. So I will let > > > Obayashi-san answer this if it's possible for them to migrate to 5.10 > > > instead? > > We have started this development project from last August, > so we have selected 5.4 as most recent and longest lifetime LTS > version at that time. > > And we have already finished to develop other device drivers, > and Video converter and CODEC drivers are now in development. > > > Why pick a kernel that doesn not support the features they require? > > That seems very odd and unwise. > > From the view point of ZeroCopy using DMABUF, is 5.4 not > mature enough, and is 5.10 enough mature ? > This is the most important point for judging migration. How do you judge "mature"? And again, if a feature isn't present in a specific kernel version, why would you think that it would be a viable solution for you to use? good luck! greg k-h