From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=52.59.177.22 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793848409; b=mncmZm82RSZI47FRK2eoYwIkH2clxcNQ2k5Tftj7WwTtMqb40I287zbLSIENzW+0G2mz 7qo/svCd6rld6DCKSHs3+efGNw+ADgCyI4751v3jcV8uolkqp7b1Ubmd+6gH89yZYvrit 84V4fo8aRtym3DJMOlJU4j25Wk3KKpCWUQ1F9m+f0QOCR7jW8KRsCuF5yoc+cD0xduRJD QJOXM0TIQAYROfk+tD/JeFK4gNnBoZtOnwYXLgvCFucNFt+xUgFRjQyzQ5cu6Wkh4RX/R 3SM67moHPe0Ndu6hs25XT1JLMR8C9a0Q+Dc6st75AaivpUsEq0H4MfJFcf6tYTxdQVg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793848409; h=DMARC-Filter:DKIM-Signature:X-QQ-mid:X-QQ-Originating-IP:Received: X-QQ-SSF:X-QQ-GoodBg:X-BIZMAIL-ID:EX-QQ-RecipientCnt:Mime-Version: Content-Transfer-Encoding:Content-Type:Date:Message-Id:Cc:Subject: From:To:X-Mailer:References:In-Reply-To:X-QQ-SENDSIZE:Feedback-ID: X-QQ-XMAILINFO:X-QQ-XMRINFO:X-QQ-RECHKSPAM; bh=elWbl+OffFQuIIm3yhMS8vybFO0kHurUhaRvfp7EAfw=; b=CwIUTuil/wzroAP7F4gKollh0Rd3XFPoXeZ9WXVMCY9ZcDRyeUa7rR94PZz2BAQLH9FY Ts0YxfsRk5sTnG+kqDdX2Wkmo4t6YmtO7Uc4ni5i7g1nYfyehvTMS6HZPvvkWNmVW+9Q6 2ioOzrimTu9l3A9tX4GROqIsciWpejjPuDU0M5xF5XbwhoUsk+2uS7g6VtCoc8AcaIIWL LD8b2s8NE66/7zbaTq3dOZfftpOajGYhE58l+hZPWGGq9xUWG2U6ZR149pdiiK2Qv9qyJ QAQ6jMe1n/83I1MG1JW4kIyzi38310PtvJpUFh3o8pmzUl7fN1rI7TZhhacj+OVwjuw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none header.from=linux.spacemit.com; spf=none smtp.mailfrom=linux.spacemit.com; dkim=pass header.d=linux.spacemit.com header.i=@linux.spacemit.com header.a=rsa-sha256 header.s=mxsw2412 header.b=rd7VFLaP; arc=none smtp.remote-ip=52.59.177.22 Received: from smtpbgeu1.qq.com (smtpbgeu1.qq.com [52.59.177.22]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5DDAE606A328; Thu, 5 Nov 2026 03:13:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 5DDAE606A328 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=linux.spacemit.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.spacemit.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.spacemit.com header.i=@linux.spacemit.com header.a=rsa-sha256 header.s=mxsw2412 header.b=rd7VFLaP DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.spacemit.com; s=mxsw2412; t=1793848257; bh=elWbl+OffFQuIIm3yhMS8vybFO0kHurUhaRvfp7EAfw=; h=Mime-Version:Date:Message-Id:Subject:From:To; b=rd7VFLaPowHCqUz/0ZqNnCNuCnedb5Ij2k/7h/uKZOENVHl6zdz2w0V2jgdyVPwnI kZkTkbtvtO6/a7bvL58wCmNWJluOiOaxIPOcgECjPKPYGZVls5JwP4+x7yYIYhBuC6 ktNKqrjNFdhCNosjBFySIALk8O0equZdRFJqS1sU= X-QQ-mid: zesmtpgz9t1793848252t934e3f3d X-QQ-Originating-IP: PzFdMtmjvpoEZUFriSo1/f1E/ApJhGnMm7BqxTlGO+Q= Received: from localhost ( [8.218.183.135]) by bizesmtp.qq.com (ESMTP) with id ; Thu, 05 Nov 2026 11:10:47 +0800 (CST) X-QQ-SSF: 0000000000000000000000000000000 X-QQ-GoodBg: 0 X-BIZMAIL-ID: 10634412826085304588 EX-QQ-RecipientCnt: 17 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Thu, 05 Nov 2026 11:10:47 +0800 Message-Id: Cc: "Bruno Banelli" , , , , "Alex Elder" , "Yixun Lan" , "Lorenzo Pieralisi" , "Krzysztof Wilczynski" , "Rob Herring" , "Bjorn Helgaas" , "Danilo Krummrich" , "Uwe Kleine-Koenig" , "Javier Martinez Canillas" , , "linux-riscv" Subject: Re: [BUG] PCI: spacemit-k1: port C probe hard-hangs a CPU with one endpoint on Milk-V Jupiter From: "Encrow Thorne" To: "Manivannan Sadhasivam" , "Encrow Thorne" X-Mailer: aerc 0.22.0-0-gc2f86b7abde3 References: <20260825052249.66921-1-bbanelli@gmail.com> In-Reply-To: X-QQ-SENDSIZE: 520 Feedback-ID: zesmtpgz:linux.spacemit.com:qybglogicsvrsz:qybglogicsvrsz3b-0 X-QQ-XMAILINFO: M6X4Jj6nmWQyum/iMKz8TxjkkJ7y/4Dfp2UGPg1Nck+98wNvcvLORLQs MTB5O+r07L6tCVLtuO8Q2MdhRqzq3TxfbCYqtA8mThs/mJQ42AJCsWlUrjwCKmKxSEB0st/ IjM7gJMpl0vK+PMSooTN8SVRqieZ9ohDChhZds9zyGQwfDtKk4TQvltDqb+9r330b+XCY+0 iL1HPFkOuIMKeReO07ijlngEnPv9NVlpprYEv2MMlXcxxS5MCLD0SaCbe3ELsyBUueufj9q i+HszP7fBQWcQV5w12SegnqyLOSnvypcpnuwZ7Jgu/+yOTcO/kzScYLVawOCiRNk7qU+/4m 4/Jpb4G2toR/IWVsOL4uL9sM0yy4EGML/hTPlt/tLUqnceEUCsxsIVnUWOvAzF4Kz292Ne/ be/SKCQ4e8d3yMAZyYOO+JgK0M6OV7fGiN35oVomkIgnSe3R+1zf1b6vLecf1n+wEev76bH P7ireGMJUrUFQ88J3Thhl8TRmVuJIsHY3bBwaGHYSjQWL4jowG6pUBpkYS1/IXP7xByB27k edIQjGjNwWIIzRQZunTLQbMYB6A5/Wv/5gRj8Gaf88nmSM54n5K44c1svqCW96ozymjZEwx aNP+VCuXVPeulZgLk/NVYczO7u9rrkJ3wGwjkSmzOAQzHeY2EoMOgqgKBMXIDXyGndvFtJO 25FLZQ89F+jPQBZ+DHVgRICDkuTQ8ff/CMGLFPa5NdTELSRaoQVVCrCeyUft5NIPe6laAfM hPXNKGIdq+rjamRW6q7/kOucLU2ryC/KKQgUIVJE52C+F3x0hXXs8hOJu6uFZLA+c3w6aX2 +bh2Vpc+n13mQuSXsPDfyNKyZRaJH8fdac44JSlLIk4ytcSsBMsBZ1mCSlIB06+ATCh4ePp o6IS5E7coP1OgX6UjxVZCmEZsebL1WeTIfXtELzTWMKuzdIAPuvrpRHWfe9WyeU2nMbI0hY bE7hxXQzVrocer1d+7Cw0BP3CPTbGcRnrkpXDx8bk7RPCmprqd6HnWyYCqZSMegoHSPu6qq HIwRdlow== X-QQ-XMRINFO: NyFYKkN4Ny6FuXrnB5Ye7Aabb3ujjtK+gg== X-QQ-RECHKSPAM: 0 On Mon Sep 21, 2026 at 4:03 PM CST, Manivannan Sadhasivam wrote: > On Mon, Sep 21, 2026 at 01:55:42PM +0800, Encrow Thorne wrote: > > [...] > >> Hi Bruno, >>=20 >> The issue was caused by a missing hardware configuration in the K1 PCIe >> initialization. >>=20 >> The PMU PCIE_CONTROL_LOGIC register contains an IGNORE_PERSTN bit (BIT(2= )). >> The hardware manual describes it as follows: >>=20 >> =E2=80=9CWhen set to 1, the PCIe controller and PHY ignore the PERSTN si= gnal from >> the link partner in both RC and EP modes.=E2=80=9D >>=20 >> This bit was not configured during RC initialization. As a result, the >> controller and PHY could still be affected by the PERSTN input during th= e >> early DBI accesses. With the Intel I225-V installed, the first DBI acces= s >> could remain pending and hang the CPU. >>=20 > Hi Mani, > What does this 'PERSTN' bit controls? PERST# or something else? PERST# is > controlled only by the Root Complex btw. Also, why does this missing regi= ster > configuration only affecting Intel I225-V endpoint and not others? > > - Mani PCIE_IGNORE_PERSTN masks the PERST# pad input to the local K1 controller and PHY. It does not control the external PERST# output. On K1, this input path remains active even in RC mode, so a low level on the pad can also hold the local controller in reset. We found a 1 kOhm pull-down on the PERST# line of the particular Intel card we tested. Together with the Jupiter board's 10 kOhm pull-up, this kept PERST# low from power-on, including during the first DBI access. The other devices we tested did not hold the line low in this way. After removing the card's pull-down, PERST# reached 3.3 V. Regards, Encrow Thorne