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Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by desiato.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1svgT1-00000003FgL-07aG; Tue, 01 Oct 2024 17:15:21 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 4F7295C4769; Tue, 1 Oct 2024 17:15:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85A75C4CEC6; Tue, 1 Oct 2024 17:15:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727802915; bh=F9k4VZbS9kuyT+dY46dvKKzolIXCmDvataW7QyUZChE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TYTZFTx//clBH30h0txuBjU8fVzOO1H+LDnSJ2R1xf6adKL6r7diYBAFx1IFqrCS5 QSc/UrKceRg+JiE3k8XRZDxyif+rlZh3ZpNtgTMYjWy5fqi13BvMrESsPsLuJGHtoY j8Pd1pCaFFlH/+ttJoIdywZ0W+j4z9c2e/aP4n4pAm0fgSe7WQRcn5hHLDtnh0Zr1p RmfZMdnqegvYCTLQUjNj5wZ+ADHnocgNnTbNd2XlN683kpG7dGAa5ldphO96bf31gL hqXgIdHRgh3+VfzTdgt4EYP2QZ6Ho4W2leVmPhA593qvBwKch4QCsi7hQc7i++apvC i/MXhiHGwkj7A== Date: Tue, 1 Oct 2024 19:15:12 +0200 From: Lorenzo Bianconi To: Bjorn Helgaas Cc: AngeloGioacchino Del Regno , 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: References: <20240930193756.GA187798@bhelgaas> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="Q6lfzaRupebapF3G" Content-Disposition: inline In-Reply-To: <20240930193756.GA187798@bhelgaas> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241001_181519_304951_1E4E3918 X-CRM114-Status: GOOD ( 19.73 ) X-BeenThere: linux-arm-kernel@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-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org --Q6lfzaRupebapF3G Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > On Mon, Sep 23, 2024 at 11:41:41AM +0200, AngeloGioacchino Del Regno wrot= e: > > 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 > > >=20 > > > Introduce the reset callback in order to avoid resetting the PCIe port > > > for Airoha EN7581 SoC. > >=20 > > EN7581 doesn't support pulling up/down PERST#?! That looks > > definitely odd, as that signal is part of the PCI-Express CEM spec. > >=20 > > Besides, there's another PERST# assertion at > > mtk_pcie_suspend_noirq()... >=20 > I agree, it doesn't smell right that this SoC doesn't have a way to > assert PERST#. >=20 > The response at > https://lore.kernel.org/r/SG2PR03MB63415DB5791C58C7EA69FF01FF682@SG2PR03M= B6341.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. >=20 > 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. Hi Bjorn, I do not have visibility on these hw details. @Hui: any update on it? Regards, Lorenzo >=20 > Bjorn --Q6lfzaRupebapF3G Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQTquNwa3Txd3rGGn7Y6cBh0uS2trAUCZvwuHwAKCRA6cBh0uS2t rI4xAP0f7H5YYjJOMPtAjiFgwoj5gmwqlZeERbA3WgcVx6T1dAEAl2Q5iAJrmoNd 9XD/DXlqF7zAN2eNFuhJqUUTcR3iggE= =iw3M -----END PGP SIGNATURE----- --Q6lfzaRupebapF3G--