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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 1B1C3C5519F for ; Thu, 12 Nov 2020 16:56:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C4400206FA for ; Thu, 12 Nov 2020 16:56:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729014AbgKLQ4P (ORCPT ); Thu, 12 Nov 2020 11:56:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53602 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728692AbgKLQ4P (ORCPT ); Thu, 12 Nov 2020 11:56:15 -0500 X-Greylist: delayed 545 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Thu, 12 Nov 2020 08:56:15 PST Received: from bmailout2.hostsharing.net (bmailout2.hostsharing.net [IPv6:2a01:37:3000::53df:4ef0:0]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1D4A7C0613D1 for ; Thu, 12 Nov 2020 08:56:14 -0800 (PST) Received: from h08.hostsharing.net (h08.hostsharing.net [83.223.95.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "*.hostsharing.net", Issuer "COMODO RSA Domain Validation Secure Server CA" (not verified)) by bmailout2.hostsharing.net (Postfix) with ESMTPS id B23B8282269E4; Thu, 12 Nov 2020 17:47:05 +0100 (CET) Received: by h08.hostsharing.net (Postfix, from userid 100393) id 80734D1743; Thu, 12 Nov 2020 17:47:05 +0100 (CET) Date: Thu, 12 Nov 2020 17:47:05 +0100 From: Lukas Wunner To: Phil Elwell Cc: Jim Quinlan , Florian Fainelli , Nicolas Saenz Julienne , Rob Herring , "maintainer:BROADCOM BCM7XXX ARM ARCHITECTURE" , "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" , "open list:PCI NATIVE HOST BRIDGE AND ENDPOINT DRIVERS" Subject: Re: [PATCH] PCI: brcmstb: Restore initial fundamental reset Message-ID: <20201112164705.GA20154@wunner.de> References: <20201112131400.3775119-1-phil@raspberrypi.com> <883066bd-2a0c-f0d8-c556-7df0e73f0503@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Thu, Nov 12, 2020 at 04:42:28PM +0000, Phil Elwell wrote: > On Thu, 12 Nov 2020 at 16:28, Jim Quinlan wrote: > > As for me considering that this line is superfluous -- which > > apparently it is not : AFAIK PERST# is always asserted from cold start > > on all Brcm STB SOCs, and I expected the same on the RPi. Asserting > > PERST# at this point in time should be a no-op. Is this not the case? > > The reason it isn't superfluous here is that when using USB to boot, > the Raspberry Pi BCM2711 firmware will already have configured the > PCIe bus once, so another reset is necessary. I think that begs the question why the firmware doesn't reset the PCIe bus before handing over control to the kernel? Thanks, Lukas