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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_MUTT 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 6C85DC31E46 for ; Wed, 12 Jun 2019 13:27:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 443F6215EA for ; Wed, 12 Jun 2019 13:27:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560346053; bh=fCiEkHOn4IM9qMiFXhbfh3OOyEoB+GLRdm6K+ZhmpQQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=KJB06a4fOk1NQGXsLw0VrHXvriDA7FviNl+5RPBjrREIFYYrrTlzVqD0u05g8A6oY Dfp6XHClerV//2BEC3+bDthJCaE94PNhmr2kEZG5M7z0q6JfQRelL0JplMZ1Ir3SJE P8sENVAZLJcoNKXXucx3lTQXuB7qX5W3kVp3Ge04= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731517AbfFLN1c (ORCPT ); Wed, 12 Jun 2019 09:27:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:53416 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728977AbfFLN1c (ORCPT ); Wed, 12 Jun 2019 09:27:32 -0400 Received: from localhost (173-25-83-245.client.mchsi.com [173.25.83.245]) (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 9B30D20866; Wed, 12 Jun 2019 13:27:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560346051; bh=fCiEkHOn4IM9qMiFXhbfh3OOyEoB+GLRdm6K+ZhmpQQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ucR0cDZmFIAHAdxv2kahFhIRw1/m7K1Irbr3F1WGoYg1wU8GwY+GO3X8PGXOr9MfO 27guwNNyMJRbXvYoPvcn2+SOMPfBEAIolvLJ1NJBgjuCA2nqD3gs+VATaw4iJSpvae 0+8MmKtLZitZu83Igh7zA0p4Wi1UecnRG/psFaa0= Date: Wed, 12 Jun 2019 08:27:30 -0500 From: Bjorn Helgaas To: Benjamin Herrenschmidt Cc: Ard Biesheuvel , Sinan Kaya , Lorenzo Pieralisi , linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, "Zilberman, Zeev" , "Saidi, Ali" Subject: Re: [PATCH/RESEND] arm64: acpi/pci: invoke _DSM whether to preserve firmware PCI setup Message-ID: <20190612132730.GB13533@google.com> References: <56715377f941f1953be43b488c2203ec090079a1.camel@kernel.crashing.org> <20190604014945.GE189360@google.com> <960c94eb151ba1d066090774621cf6ca6566d135.camel@kernel.crashing.org> <20190604124959.GF189360@google.com> <20190611233908.GA13533@google.com> <97fd2516fdde7f9f01688af426c103806f68dd2c.camel@kernel.crashing.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <97fd2516fdde7f9f01688af426c103806f68dd2c.camel@kernel.crashing.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Wed, Jun 12, 2019 at 10:06:06AM +1000, Benjamin Herrenschmidt wrote: > On Tue, 2019-06-11 at 18:39 -0500, Bjorn Helgaas wrote: > > This is fine, but can we make a tiny step toward doing this in generic > > code instead of adding more arch-specific stuff? > > > > E.g., evaluate the _DSM in the generic acpi_pci_root_add(), set a > > "preserve_config" bit in the struct acpi_pci_root, and test the bit > > here? > > I'd rather have the flag in the host bridge no ? Oh, of course, that would make more sense. > Talking of which, look at the ongoing discussion I have with Lorenzo > when it comes to pci_bus_claim_resources vs. what x86 does, I'd love > for you to chime in. I'd like to try to consolidate things further > accross architectures but there might be reasons I don't see as to why > things are different in that area, so ... I don't know any reasons why things are different per arch. In most cases I suspect FUD. Speaking of which, *this* patch looks like FUD because it essentially says "Linux shouldn't change the PCI configuration on this system" but it offers no explanation of *why* the config needs to be preserved. I would really like some note like "run-time firmware depends on the addresses of device X". Bjorn