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{ "id": 2219761, "url": "http://patchwork.ozlabs.org/api/covers/2219761/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-pci/cover/20260404-t_power_on_fux-v4-0-2891391177f4@oss.qualcomm.com/", "project": { "id": 28, "url": "http://patchwork.ozlabs.org/api/projects/28/?format=api", "name": "Linux PCI development", "link_name": "linux-pci", "list_id": "linux-pci.vger.kernel.org", "list_email": "linux-pci@vger.kernel.org", "web_url": null, "scm_url": null, "webscm_url": null, "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20260404-t_power_on_fux-v4-0-2891391177f4@oss.qualcomm.com>", "list_archive_url": null, "date": "2026-04-04T08:17:17", "name": "[v4,0/3] PCI: qcom: Program T_POWER_ON value for L1.2 exit timing", "submitter": { "id": 89908, "url": "http://patchwork.ozlabs.org/api/people/89908/?format=api", "name": "Krishna Chaitanya Chundru", "email": "krishna.chundru@oss.qualcomm.com" }, "mbox": "http://patchwork.ozlabs.org/project/linux-pci/cover/20260404-t_power_on_fux-v4-0-2891391177f4@oss.qualcomm.com/mbox/", "series": [ { "id": 498705, "url": "http://patchwork.ozlabs.org/api/series/498705/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-pci/list/?series=498705", "date": "2026-04-04T08:17:17", "name": "PCI: qcom: Program T_POWER_ON value for L1.2 exit timing", "version": 4, "mbox": "http://patchwork.ozlabs.org/series/498705/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/covers/2219761/comments/", "headers": { "Return-Path": "\n <linux-pci+bounces-51864-incoming=patchwork.ozlabs.org@vger.kernel.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "linux-pci@vger.kernel.org" ], "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=qualcomm.com header.i=@qualcomm.com header.a=rsa-sha256\n header.s=qcppdkim1 header.b=SF7xY7+j;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com\n header.a=rsa-sha256 header.s=google header.b=eK9sRvDl;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c0a:e001:db::12fc:5321; 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charset=\"utf-8\"", "Content-Transfer-Encoding": "8bit", "X-B4-Tracking": "v=1; b=H4sIAA3J0GkC/3XM0QrCIBTG8VcJr3N4jptmV71HxFhOS6i5dFuL2\n LvnBtFFdXPgf+D7PUk0wZlItqsnCWZw0fkmRb5eEX2umpOhrk5NkGEBwHLala2/m1D6prT9SCW\n rtdhwKVUOJI3aYKwbF3B/SH12sfPhsfgDzN+/1AAUqDkWCoTJpa3lzseY3frqov31mqVDZnHAt\n yIYIv9SkDKKTCsEFCiZ+qPwj8IBvhSeFHUECzVTWlj+Q5mm6QW7UbCDPwEAAA==", "X-Change-ID": "20251104-t_power_on_fux-70dc68377941", "To": "Manivannan Sadhasivam <mani@kernel.org>,\n Lorenzo Pieralisi <lpieralisi@kernel.org>, =?utf-8?q?Krzysztof_Wilczy=C5=84?=\n\t=?utf-8?q?ski?= <kwilczynski@kernel.org>, Rob Herring <robh@kernel.org>,\n Bjorn Helgaas <bhelgaas@google.com>, Jingoo Han <jingoohan1@gmail.com>", "Cc": "linux-pci@vger.kernel.org, linux-arm-msm@vger.kernel.org,\n linux-kernel@vger.kernel.org, mayank.rana@oss.qualcomm.com,\n quic_vbadigan@quicinc.com,\n Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>,\n Shawn Lin <shawn.lin@rock-chips.com>", "X-Mailer": "b4 0.14.2", "X-Developer-Signature": "v=1; a=ed25519-sha256; t=1775290641; l=2785;\n i=krishna.chundru@oss.qualcomm.com; s=20230907; h=from:subject:message-id;\n bh=qdnUNga94uLcJe/gNdftrxaAv+ogb/QdF4r+eQglgdQ=;\n b=JI+Ew2L2ICtllEYmUY4chUJtRoaYvl+O1EM5DBsPbqNJfNAE1mfaqrrutoR/rNwACTrmW2c7k\n 6wjUi3QwBSYACWTORG6JR0+jW7GqehdLZsf0DsEdkLF0MyJO4iGnYA/", "X-Developer-Key": "i=krishna.chundru@oss.qualcomm.com; a=ed25519;\n pk=10CL2pdAKFyzyOHbfSWHCD0X0my7CXxj8gJScmn1FAg=", "X-Proofpoint-Spam-Details-Enc": "AW1haW4tMjYwNDA0MDA3MiBTYWx0ZWRfX/z+PR+xlEkfj\n nXk/vowmD21wfEFD9cKrhZKeMJmxDSSft0G31Nyd+h+jRpVJNC0TmwhclZlkXp5xxHf2q6AJhx2\n WkRrn5j8qoYj9ue6lnDt3noE9sNNVxxtJr2armbW0MpZywFZ2dK3Afx5+E7X9dUp27QC7vgS2RQ\n UBQ56O9B5Itbrz1Osup3/0uPRS1JEXHle6EQDXwtH23X+iL0659bX/P9P+wfg1d2l0c87R5P9R6\n iI6hWm4DAKFEt7ISIQhzK1aAuZOLFEqg7UlNcTEo6B0+ma/8g1r3gUVxTy3Bo9zCZrODwRjBKWt\n 0Jo4pRP1cwwYShZXB94u2l/0vPF3s07VFmDEiPtEfdhlyx1IreObpjn76YNeh6J8j/PCsGD2uEK\n G+V79ogBE4hMj7Q1LdpXoXfNIqo7yT5tuBRDp+RtEx2GDdEVR79Mo3UAgujfY9Tiz7A7fotAwhM\n QEluRmidVQvjuEYUdTw==", "X-Proofpoint-GUID": "B_U5-8f3cG5zc457GLexKUCSbU4lrO53", "X-Authority-Analysis": "v=2.4 cv=MIptWcZl c=1 sm=1 tr=0 ts=69d0c917 cx=c_pps\n a=Qgeoaf8Lrialg5Z894R3/Q==:117 a=ZePRamnt/+rB5gQjfz0u9A==:17\n a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=s4-Qcg_JpJYA:10\n a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=DJpcGTmdVt4CTyJn9g5Z:22\n a=VwQbUJbxAAAA:8 a=EUspDBNiAAAA:8 a=8_GxwEYHqknyFer8HbIA:9 a=3ZKOabzyN94A:10\n a=QEXdDO2ut3YA:10 a=x9snwWr2DeNwDh03kgHS:22", "X-Proofpoint-ORIG-GUID": "B_U5-8f3cG5zc457GLexKUCSbU4lrO53", "X-Proofpoint-Virus-Version": "vendor=baseguard\n engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49\n definitions=2026-04-03_07,2026-04-03_01,2025-10-01_01", "X-Proofpoint-Spam-Details": "rule=outbound_notspam policy=outbound score=0\n clxscore=1015 malwarescore=0 suspectscore=0 lowpriorityscore=0\n priorityscore=1501 adultscore=0 impostorscore=0 phishscore=0 bulkscore=0\n spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound\n adjust=0 reason=mlx scancount=1 engine=8.22.0-2603050001\n definitions=main-2604040072" }, "content": "The T_POWER_ON indicates the time (in μs) that a Port requires the port\non the opposite side of Link to wait in L1.2.Exit after sampling CLKREQ#\nasserted before actively driving the interface. This value is used by\nthe ASPM driver to compute the LTR_L1.2_THRESHOLD.\n\nCurrently, qcom root port exposes T_POWER_ON value of zero in the L1SS\ncapability registers, leading to incorrect LTR_L1.2_THRESHOLD calculations,\nwhich can result in improper L1.2 exit behavior and can trigger AER's.\n\nIn this series, qcom controller drivers read the devicetree property\n\"t-power-on\" which got merged recently[1], and use that value to over\nwrite default/wrong value.\n\nTo convert T_POWER_ON in to T_POWER_ON_SCALE & T_POWER_ON_VALUE created\na pcie_encode_t_power_on() helper in aspm.c and also created\ndw_pcie_program_t_power_on() helper for other drivers to use these\nhelpers.\n\nLink [1]: https://lore.kernel.org/all/20260205093346.667898-1-krishna.chundru@oss.qualcomm.com/\n\nSigned-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>\n---\nChanges in v4:\n- calculate maxv from PCI_L1SS_CTL2_T_PWR_ON_VALUE to PCI_L1SS_CAP_P_PWR_ON_VALUE (Mani).\n- added a todo to move the reading the devicetree from qcom driver to\n dwc once multi root port parsing support is added (Mani).\n- Link to v3: https://lore.kernel.org/r/20260311-t_power_on_fux-v3-0-9b1f1d09c6f3@oss.qualcomm.com\n\nChanges in v3:\n- move pcie_encode_t_power_on() include/linux/pci.h to\n drivers/pci/pci.h (Bjorn).\n- couple of changes in commit text and variable name like t_power_on (Bjorn).\n- remove return 0 from qcom_pcie_configure_ports (Bjorn).\n- used FIELD_MODIFY instead of FIELD_PREP (Bjorn).\n- Link to v2: https://lore.kernel.org/r/20260223-t_power_on_fux-v2-0-20c921262709@oss.qualcomm.com\n\nChanges in v2:\n- Instead of hard coding the values in the driver, created a devicetree\n property \"t-power-on\" to program it (Bjorn & Mani).\n- Link to v1: https://lore.kernel.org/r/20251104-t_power_on_fux-v1-1-eb5916e47fd7@oss.qualcomm.com\n\n---\nKrishna Chaitanya Chundru (3):\n PCI/ASPM: Add helper to encode L1SS T_POWER_ON fields\n PCI: dwc: Add helper to Program T_POWER_ON\n PCI: qcom: Program T_POWER_ON\n\n drivers/pci/controller/dwc/pcie-designware.c | 28 +++++++++++++++++++\n drivers/pci/controller/dwc/pcie-designware.h | 1 +\n drivers/pci/controller/dwc/pcie-qcom.c | 14 ++++++++++\n drivers/pci/pci.h | 2 ++\n drivers/pci/pcie/aspm.c | 40 ++++++++++++++++++++++++++++\n 5 files changed, 85 insertions(+)\n---\nbase-commit: 7ca6d1cfec80ebe46cc063f3284c5896c344d9a1\nchange-id: 20251104-t_power_on_fux-70dc68377941\n\nBest regards," }