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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D13E6C433F5 for ; Thu, 7 Oct 2021 10:33:33 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 998E760FC3 for ; Thu, 7 Oct 2021 10:33:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 998E760FC3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=sjbi5P00WYElfwix0Wn+TBUC31B1gEF+ts32bPbclyE=; b=iB4pCftrKdBg5S MmwgomQ4sLVqF1RrG9i/honj91QLNB/Hgrqe9nVImSRQ9LnIhiAosgtym+PW2B7M8AnYHqkx4laQ4 GPrDURcK2zSh3DIEQBpSvhbTbf5AfehYrgsy23gNZaqna2lwJXcrl24DMLOFWv0kP2I+qD01jk2k1 ibIV1TW8rGNFQ41SMr+eKmKIL3ckSXsfnkKc1Qxs1pQnCjaLgVp1MvkFb/vfLcRGsJX2+0XCXVkuZ onXXVUlKF5O37ZNEbp+wZIpV05qviuappOxxg4CA8rncY6xOwuB37MdKKMWI28Bt8ftHsr7d0SQEN qfCR3xLhKc3v10HYLuMw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mYQgk-00GuFY-CI; Thu, 07 Oct 2021 10:31:46 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mYQgf-00GuEL-Mk for linux-arm-kernel@lists.infradead.org; Thu, 07 Oct 2021 10:31:43 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id BFC7D60FC3; Thu, 7 Oct 2021 10:31:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1633602701; bh=rjKhAROtKEemtbK1MVWHzDSSAHwzCKKa7aWIBII+u6M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TVp1j6rPJYoLyLt69ZNT1udPquyr/jFRQSTF7wMlB1LXK+gRz7W1gztYG8NuWXV5K 3k+GYtqr+AHd7kjE7khwdWutNiVXOERGnxcRBRzRylGTlRseYSSAz5Ah5koaYjtfiV CaJq3tPOwQ2j6tYoxFbKJj/yQKXeJEukMZ4RPdYc= Date: Thu, 7 Oct 2021 12:31:39 +0200 From: Greg Kroah-Hartman To: Zev Weiss Cc: Andy Shevchenko , OpenBMC Maillist , Jeremy Kerr , Joel Stanley , Rob Herring , devicetree , Andrew Jeffery , Frank Rowand , "Rafael J. Wysocki" , Andy Shevchenko , Andrew Morton , Francis Laniel , Kees Cook , Andrey Konovalov , Jonathan Cameron , Daniel Axtens , Alexey Dobriyan , Dan Williams , Daniel Vetter , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Heiner Kallweit , Nick Desaulniers , Linux Kernel Mailing List , linux-arm Mailing List , "moderated list:ARM/ASPEED MACHINE SUPPORT" Subject: Re: [PATCH 0/9] Dynamic DT device nodes Message-ID: References: <20211007000954.30621-1-zev@bewilderbeest.net> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211007_033141_804263_D5F9A3DE X-CRM114-Status: GOOD ( 30.14 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Oct 07, 2021 at 02:05:41AM -0700, Zev Weiss wrote: > On Thu, Oct 07, 2021 at 12:04:41AM PDT, Andy Shevchenko wrote: > > On Thu, Oct 7, 2021 at 3:10 AM Zev Weiss wrote: > > > This patch series is in some ways kind of a v2 for the "Dynamic > > > aspeed-smc flash chips via 'reserved' DT status" series I posted > > > previously [0], but takes a fairly different approach suggested by Rob > > > Herring [1] and doesn't actually touch the aspeed-smc driver or > > > anything in the MTD subsystem, so I haven't marked it as such. > > > > > > To recap a bit of the context from that series, in OpenBMC there's a > > > need for certain devices (described by device-tree nodes) to be able > > > to be attached and detached at runtime (for example the SPI flash for > > > the host's firmware, which is shared between the BMC and the host but > > > can only be accessed by one or the other at a time). > > > > This seems quite dangerous. Why do you need that? > > Sometimes the host needs access to the flash (it's the host's firmware, > after all), sometimes the BMC needs access to it (e.g. to perform an > out-of-band update to the host's firmware). To achieve the latter, the > flash needs to be attached to the BMC, but that requires some careful > coordination with the host to arbitrate which one actually has access to it > (that coordination is handled by userspace, which then tells the kernel > explicitly when the flash should be attached and detached). > > What seems dangerous? > > > Why can't device tree overlays be used? > > I'm hoping to stay closer to mainline. The OpenBMC kernel has a documented > policy strongly encouraging upstream-first development: > https://github.com/openbmc/docs/blob/master/kernel-development.md > > I doubt Joel (the OpenBMC kernel maintainer) would be eager to start > carrying the DT overlay patches; I'd likewise strongly prefer to avoid > carrying them myself as additional downstream patches. Hence the attempt at > getting a solution to the problem upstream. Then why not work to get device tree overlays to be merged properly? Don't work on a half-of-a-solution when the real solution is already here. thanks, greg k-h _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel