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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B3636C433EF for ; Wed, 24 Nov 2021 09:22:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232907AbhKXJZk (ORCPT ); Wed, 24 Nov 2021 04:25:40 -0500 Received: from hostingweb31-40.netsons.net ([89.40.174.40]:39902 "EHLO hostingweb31-40.netsons.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232105AbhKXJZi (ORCPT ); Wed, 24 Nov 2021 04:25:38 -0500 Received: from [79.2.93.196] (port=52040 helo=[192.168.101.73]) by hostingweb31.netsons.net with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1mpoU0-0008zx-5Q; Wed, 24 Nov 2021 10:22:28 +0100 Subject: Re: [PATCH v3 1/3] PCI: apple: Follow the PCIe specifications when resetting the port To: Marc Zyngier , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org Cc: =?UTF-8?Q?Pali_Roh=c3=a1r?= , Alyssa Rosenzweig , Lorenzo Pieralisi , Bjorn Helgaas , Mark Kettenis , kernel-team@android.com References: <20211123180636.80558-1-maz@kernel.org> <20211123180636.80558-2-maz@kernel.org> From: Luca Ceresoli Message-ID: <60f24740-156e-f679-e77b-3c60ced5b41b@lucaceresoli.net> Date: Wed, 24 Nov 2021 10:22:27 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20211123180636.80558-2-maz@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - hostingweb31.netsons.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - lucaceresoli.net X-Get-Message-Sender-Via: hostingweb31.netsons.net: authenticated_id: luca+lucaceresoli.net/only user confirmed/virtual account not confirmed X-Authenticated-Sender: hostingweb31.netsons.net: luca@lucaceresoli.net X-Source: X-Source-Args: X-Source-Dir: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 23/11/21 19:06, Marc Zyngier wrote: > While the Apple PCIe driver works correctly when directly booted > from the firmware, it fails to initialise when the kernel is booted > from a bootloader using PCIe such as u-boot. > > That's beacuse we're missing a proper reset of the port (we only > clear the reset, but never assert it). > > The PCIe spec requirements are two-fold: > > - #PERST must be asserted before setting up the clocks, and > stay asserted for at least 100us (Tperst-clk). > > - Once #PERST is deasserted, the OS must wait for at least 100ms > "from the end of a Conventional Reset" before we can start talking > to the devices > > Implementing this results in a booting system. > > Fixes: 1e33888fbe44 ("PCI: apple: Add initial hardware bring-up") > Acked-by: Pali Rohár > Signed-off-by: Marc Zyngier > Cc: Alyssa Rosenzweig > Cc: Lorenzo Pieralisi > Cc: Bjorn Helgaas > > --- > drivers/pci/controller/pcie-apple.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c > index 1bf4d75b61be..957960a733c4 100644 > --- a/drivers/pci/controller/pcie-apple.c > +++ b/drivers/pci/controller/pcie-apple.c > @@ -539,13 +539,23 @@ static int apple_pcie_setup_port(struct apple_pcie *pcie, > > rmw_set(PORT_APPCLK_EN, port->base + PORT_APPCLK); > > + /* Engage #PERST before setting up the clock */ "Assert" is the verb typically used instead of "Engage". With this fixed, or even without as this is a pretty urgent fix: Reviewed-by: Luca Ceresoli -- Luca