From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.221.170 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792441519; b=4EGBH6EBzA148hzT7P41a4snN7D8ZYXogTw2oaSTBYTAHs2u2uizHZehcfTHal3KC4yZ PkEl1xy4H/ghcAundyZmvaw/ftL4gK+Yij1/K8JN3z6k1NemYKQ/r6nQIUx/4eZ3BoQkR SaXH9rqXejZsRWmv7OJMB3fpNgWgwJoloozBgqfiDlsJ0QjLFul+sPtLVWWBVISGRWeLh HUgHw+3MFyejDVss8WsUpgDN2F9GLKQGCgL0LRXllGALa7MbcxRpfKrVG+4Tm4PM8pzvK gNzsyjI51tmG4q0hYacoA6gCZ9XIa5VWM5/De2li0LTla7kT6FVwCHaX3lM7OZ6HfXw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792441519; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: From:To:Cc:Subject:Date:Message-ID:X-Mailer:In-Reply-To:References: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=4q9LZR8lO5Ut3wMXLJYCt156smic9s4b9LeYVAkPcUw=; b=Qc4kSbzPL8d2WgnwF+840GwDa+WUp9wsKx0nJEVWW2EUsOxLT/CGrIZu3xesvSKpQSME /uMkPeED2/iFbhojnGdkaSJ6NTKuv9ykWY6vDhMO00rZAdx083aTO/Fn2P2YDvoJw6hQT 5soZ71W5Xdbfc8rEDUVgwD68WtmMAMg8ccpRwMEcGZtj6dtNtFJPyGagVvvvjkP5k/FAn g+AASNlh93W4xen6lnE6V878/hTBfGew+99dyg/yfycEHRDrUtD6l/Ag+XwiMU0m9ogF7 QSzfgYTCYj2mE/hsZrzIgSmQk74/Qp2I1StaPNXbOfLLgtEhqEz2JbS1PeYaGV43oQg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20251104 header.b=b3n3iESw; arc=none smtp.remote-ip=209.85.221.170 Received: from mail-vk1-f170.google.com (mail-vk1-f170.google.com [209.85.221.170]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C90FD606A31B for ; Mon, 19 Oct 2026 20:25:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org C90FD606A31B Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20251104 header.b=b3n3iESw Received: by mail-vk1-f170.google.com with SMTP id 71dfb90a1353d-5e189660cbdso1740700e0c.1 for ; Mon, 19 Oct 2026 13:25:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1792441518; x=1793046318; darn=vger.kernel.org; h=content-transfer-encoding:content-type:mime-version:references :in-reply-to:message-id:date:subject:cc:to:from:from:to:cc:subject :date:message-id:reply-to:content-type; bh=4q9LZR8lO5Ut3wMXLJYCt156smic9s4b9LeYVAkPcUw=; b=b3n3iESwm43cGITB3Nstp67NHJ9NaTjO8YW6SzFN0R8RveeAZUxnbsu+4Ef/Yhe8AO 33evcLFrWK+B8KyjJKEmJjStJ/bZyJgtZtA2T0PqY6W3za0WygokmuekeVF+Z+DLHfH2 WKhuUF6W/vwLY0XegluMV/fhj8GXFSAOQ5f1Eu8vHmsuZ5oSpG0SGNbWFHYj6jnCdzX5 ROT3sXIxosF1+cjjbog8StFejCo9gi+gX2Yx/llkyAzTBdTMpYwHx03axYPQb9d0/+vh /srxTzpK1bl19mWL8u/GwvoMBQreIJLXkEnnTGlJqBCUh64sdJIzaY56Hqn/MUsNd/Sw V6DQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1792441518; x=1793046318; h=content-transfer-encoding:content-type:mime-version:references :in-reply-to:message-id:date:subject:cc:to:from:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=4q9LZR8lO5Ut3wMXLJYCt156smic9s4b9LeYVAkPcUw=; b=Qo87inTxsTtwXFeaxrbZMd4jrvYaKyz26dD4unjs2l82I5sqPAmHoL2ambU6ndM9Ep brtKvmyuFes8YbkJPTrqiHqpUJO2uDdTyKbhkIGeFh/N0w127AQvl/J8T7LLKf8cC26H OKKklfDLBwERO0EzTq/M8Al4H1WAlMss9hnWmN82FR1s98HYqwIiKcUYukn48No2fVeo 9BqIBPmJFOILCN1EAbqmn9kuKil6h7f5VMWK1sAnJ7p2anNfNtmT4ohL9MTxS8hlNUqM hDPuwvktKUDLC3+DO+UqTFC8TsYAXpHiNt6i0KcVAbZk+tjeWswyZs4QkXfEXmPCUvCx L7Vw== X-Forwarded-Encrypted: i=1; AKwUvBz4do2xR1A47CNTiJBREHkViI8UOyYxaRUounKGfu0fuMzSzgomZLJ1ba3WWW363FokKoszqEEA5T8XWFE=@vger.kernel.org X-Gm-Message-State: AFq9FYJGIdE6YphAXP6xaLV2WiFxjF12Dss5pl3ykfkNGkXkrZxPjXQK wSI5uqSlVWZWeToYHjlmUGPGa8ylRAdHnt+enHI3qi1cTEr2j5fvS0ks X-Gm-Gg: AYBFou2T2KzOw17tnBLhiFt5GX/jZZasS60g26BbcAJyQ+IxeYh48pTxiFWG7A9oisB wgKmsaSF8QVAbz6esGt3J5+4OrkKvVuXLJFqak/rEVFbyu5QJPpFxtyzZ1HtelLdOjuvwDB/tMk 2YQDMcGn885AuBWeAC1WWfi4Z5pDS3vJIjSJmBSklfdGWGix4xMwP9A5t0F9c8IRcgTvQzzzwfc 6fwpjb1/1TUg1DMEWA3rKRBTLZFQBhnFlrVccSpEbYhq5ZcJ6jklC/iETtpxGKBoI3S0QcJdKaq UZPlIqdQ1oivS5MR1VuTXi825kckv5HyziW1S8ZRDLu17Vag8OhZlHBKK3WQwj5Zg/nmaPMoAtX Oo+kfl4BzFbYycHyxMZJlBlY+IyCq+X7P21lhbI2PrNdauR4P+jSomlS9iXVaE1iLe3BNAsssoF DHUp4NT8FRIyh2dzEUfp7b4aAdWRevLy/98n3yd1eLjb/8Yy4t2n2eVnS4MalmBnIADrdcz/TPo d5AVrea X-Received: by 2002:a05:6122:32d4:b0:5e9:176f:a548 with SMTP id 71dfb90a1353d-5eaa9eb7e68mr3507437e0c.0.1792441517762; Mon, 19 Oct 2026 13:25:17 -0700 (PDT) Received: from maclinux ([2803:c600:9110:8ba5:1c75:eeaa:b22f:20dc]) by smtp.gmail.com with ESMTPSA id 71dfb90a1353d-5ea9b128725sm11194050e0c.0.2026.10.19.13.25.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Oct 2026 13:25:17 -0700 (PDT) From: =?UTF-8?q?Francisco=20Beltr=C3=A1n=20Millal=C3=A9n?= To: Bjorn Helgaas , linux-pci@vger.kernel.org Cc: Bjorn Helgaas , Alan Stern , Greg Kroah-Hartman , Lukas Wunner , Farhan Ali , Andreas Noever , Mika Westerberg , Yehezkel Bernat , Darrell Gum , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 2/2] PCI: Do not mistake an absent device for an active link Date: Mon, 19 Oct 2026 17:24:45 -0300 Message-ID: <20261019202445.38259-3-fbeltranmillalen@gmail.com> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261019202445.38259-1-fbeltranmillalen@gmail.com> References: <20261019202445.38259-1-fbeltranmillalen@gmail.com> 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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When an inaccessible bridge's Link Status register reads as 0xffff, both PCI_EXP_LNKSTA_DLLLA and PCI_EXP_LNKSTA_LT appear set. The link wait code then takes the inaccessible bridge for an active link: - pci_bridge_wait_for_secondary_bus(), for ports up to 5 GT/s, decides that the link is up and waits PCIE_RESET_READY_POLL_MS for the device below it; - pcie_wait_for_link_status(), used for faster ports and by pcie_retrain_link(), reports success at once when waiting for an active link, and times out after PCIE_LINK_RETRAIN_TIMEOUT_MS when waiting for LT to clear. Treat an all-ones read as the device being gone. All callers of pcie_wait_for_link_status() and pcie_retrain_link() treat any non-zero return as failure. On a MacBookPro14,3 whose Thunderbolt controller does not come back from S3, the downstream ports of the controller are 2.5 GT/s ports that no longer answer. Resume spent about 65 seconds waiting for the xHCI controller behind one of them ("not ready 65535ms after resume"); with the pci_bridge_wait_for_secondary_bus() change it gives up on that controller after about one second. That machine never reaches pcie_wait_for_link_status() in this situation, so that part has not been tested. Assisted-by: LLM Signed-off-by: Francisco Beltrán Millalén Tested-by: Darrell Gum --- v3: - No change, apart from adding Darrell's Tested-by from v2 (was 3/3). v2: - Also cover pcie_wait_for_link_status(). drivers/pci/pci.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index eacaa1e71a83..24b51dd0f9cc 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4604,8 +4604,8 @@ static int pci_pm_reset(struct pci_dev *dev, bool probe) * @use_lt: Use the LT bit if TRUE, or the DLLLA bit if FALSE. * @active: Waiting for active or inactive? * - * Return 0 if successful, or -ETIMEDOUT if status has not changed within - * PCIE_LINK_RETRAIN_TIMEOUT_MS milliseconds. + * Return 0 if successful, -ENODEV if @pdev is not accessible, or -ETIMEDOUT + * if status has not changed within PCIE_LINK_RETRAIN_TIMEOUT_MS milliseconds. */ static int pcie_wait_for_link_status(struct pci_dev *pdev, bool use_lt, bool active) @@ -4620,6 +4620,9 @@ static int pcie_wait_for_link_status(struct pci_dev *pdev, end_jiffies = jiffies + msecs_to_jiffies(PCIE_LINK_RETRAIN_TIMEOUT_MS); do { pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnksta); + /* All ones means @pdev is gone; it would look like an active link */ + if (PCI_POSSIBLE_ERROR(lnksta)) + return -ENODEV; if ((lnksta & lnksta_mask) == lnksta_match) return 0; msleep(1); @@ -4642,8 +4645,9 @@ static int pcie_wait_for_link_status(struct pci_dev *pdev, * according to @use_lt. It is not verified whether the use of the DLLLA * bit is valid. * - * Return 0 if successful, or -ETIMEDOUT if training has not completed - * within PCIE_LINK_RETRAIN_TIMEOUT_MS milliseconds. + * Return 0 if successful, -ENODEV if @pdev is not accessible, or -ETIMEDOUT + * if training has not completed within PCIE_LINK_RETRAIN_TIMEOUT_MS + * milliseconds. */ int pcie_retrain_link(struct pci_dev *pdev, bool use_lt) { @@ -4876,8 +4880,10 @@ int pci_bridge_wait_for_secondary_bus(struct pci_dev *dev, char *reset_type) if (!dev->link_active_reporting) return -ENOTTY; + /* All ones means @dev is gone; it would look like an active link */ pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &status); - if (!(status & PCI_EXP_LNKSTA_DLLLA)) + if (PCI_POSSIBLE_ERROR(status) || + !(status & PCI_EXP_LNKSTA_DLLLA)) return -ENOTTY; return pci_dev_wait(child, reset_type,