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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 3F816CDD1D5 for ; Mon, 30 Sep 2024 19:39:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:References: List-Owner; bh=uqNRevo7/gz488fiTqhhJjGGO3OeNRssLhg7JzCxscc=; b=Ix3KHUhOEheeg1 Qii0uUqbfRONpfl2/81qIwfrg3Fi3R8dA709hXSUq0/jQ943wB3PvmDhzEI/ImYlL+xcLINrzoKUT 6c+RijbWvZA+E0ADLM7gJqN0qdN7eV/Ygji55fV95ZmPuX5ahvax/qGI7CP3fybZGC2kbFl6EygcE jUevk3UYvYnN6tRMt2x0jATzn3TNfBnBbyZkFIOVziNZXQ5cz0bi5Qt7aN3axyIp6tjNmif9tQORy P5BM2oRS6jAE3G0PNOPosa75WKvnVmuF0FocHvTlF7Sd80moOnbSXduUpQJeM8Qc4AP8QmMvf6dme gdSp61r9HGcd/ftLRgvw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1svMEl-00000000eUG-16CJ; Mon, 30 Sep 2024 19:39:15 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1svMDY-00000000eMg-0Kkj; Mon, 30 Sep 2024 19:38:01 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id B23A95C5415; Mon, 30 Sep 2024 19:37:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2BA59C4CEC7; Mon, 30 Sep 2024 19:37:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727725078; bh=bd1W1edyxyIMzyL2oVwBIlRMv4WpY7BdgJEv7EeGadU=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=Bj5fAJyXTmlHX0a4DRvSQuSyLlHOQXv4RSMwtiCTmAKV4ifAt0Cy3jB3IVi5N7NqX juZkVo9JxoiHBdA8ynQTQaiKOmZk+y9W3Bpm036nNJqIJOlt9ScFiRBblEUv62GkqX 60MhMh2HSYCoz3tT0MmMALx4gTBZjJg+/TTDfhcQA+2UKxMPf3m/HXJz8pynmwSSXK 8eglbwfrGxOHYOC7T/QfAtG5+e8+gEpeudcSExGwhGejwdojBWzuiY5gT70m63m6Kz niXI0iq95UQxVnC7QOKBxAsBrOO1Do+P19DXKjDY9gCvH1hjSrOSeO+Z9IkwHyk+/G 294KSdkwmdVVA== Date: Mon, 30 Sep 2024 14:37:56 -0500 From: Bjorn Helgaas To: AngeloGioacchino Del Regno Cc: Lorenzo Bianconi , Ryder Lee , Jianjun Wang , Lorenzo Pieralisi , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Rob Herring , Bjorn Helgaas , Matthias Brugger , Christian Marangi , linux-pci@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, upstream@airoha.com, Hui Ma Subject: Re: [PATCH] PCI: mediatek-gen3: Avoid PCIe resetting for Airoha EN7581 SoC Message-ID: <20240930193756.GA187798@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240930_123800_205147_09FFDCDA X-CRM114-Status: GOOD ( 14.10 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org On Mon, Sep 23, 2024 at 11:41:41AM +0200, AngeloGioacchino Del Regno wrote: > Il 20/09/24 10:26, Lorenzo Bianconi ha scritto: > > The PCIe controller available on the EN7581 SoC does not support reset > > via the following lines: > > - PCIE_MAC_RSTB > > - PCIE_PHY_RSTB > > - PCIE_BRG_RSTB > > - PCIE_PE_RSTB > > > > Introduce the reset callback in order to avoid resetting the PCIe port > > for Airoha EN7581 SoC. > > EN7581 doesn't support pulling up/down PERST#?! That looks > definitely odd, as that signal is part of the PCI-Express CEM spec. > > Besides, there's another PERST# assertion at > mtk_pcie_suspend_noirq()... I agree, it doesn't smell right that this SoC doesn't have a way to assert PERST#. The response at https://lore.kernel.org/r/SG2PR03MB63415DB5791C58C7EA69FF01FF682@SG2PR03MB6341.apcprd03.prod.outlook.com suggests that maybe there's a hardware defect that means asserting PERST# doesn't work correctly? But surely firmware must have a way of asserting PERST#, at least at boot time. If this is truly a hardware defect and we really can't assert PERST#, please say that this is a defect in the commit log so people don't think that lack of PERST# is an acceptable thing. Bjorn