From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DCD59198E84 for ; Mon, 30 Sep 2024 19:37:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727725078; cv=none; b=ioQf5Y1hgZEt1AI/RRUvBFjh+Toa07Dz5Cq1OFUNYycdWOq1RprHZhKzNm2ASu6jH54Y8NPLsDNjaRlvHSB4oD5Io5i3OoydpzkSpCL8+vp50NwEZzhwt1gtXks6yPgO77hqpLvhnVzxaMPybVBatiyrMQ2VbSLk4XDeeZjaKIA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727725078; c=relaxed/simple; bh=bd1W1edyxyIMzyL2oVwBIlRMv4WpY7BdgJEv7EeGadU=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=SBWzqvM787mWpxgzr8Zs1hHzVOXzUfRxsQKnLU2PsOU5LcCaF2/7RCZEwYS81/Aay3dK38Y+HfjTb3xchGH9Oj9GehW1V6wU8qvByuaqoOosc3b81UdsGVuz8YC646hUt2T9VWYvFdqzfkGitAWuLOQQ5wPDFAmN6iwoswvHKn4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Bj5fAJyX; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Bj5fAJyX" 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> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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