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Wed, 09 Sep 2026 03:50:33 -0700 (PDT) X-Received: by 2002:a05:620a:2913:b0:939:5924:e319 with SMTP id af79cd13be357-939914ccf18mr2247437485a.0.1788951032996; Wed, 09 Sep 2026 03:50:32 -0700 (PDT) Received: from [192.168.202.12] ([178.235.128.140]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6a839344fe8sm2022203a12.5.2026.09.09.03.50.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 09 Sep 2026 03:50:31 -0700 (PDT) Message-ID: Date: Wed, 9 Sep 2026 12:50:29 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 1/3] PCI: host-common: Fix early bus-walk exit in d3cold_possible() To: Krishna Chaitanya Chundru , Jingoo Han , Manivannan Sadhasivam , Lorenzo Pieralisi , =?UTF-8?Q?Krzysztof_Wilczy=C5=84ski?= , Rob Herring , Bjorn Helgaas Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org References: <20260905-shutdown-v5-0-f0c6bafa1d4f@oss.qualcomm.com> <20260905-shutdown-v5-1-f0c6bafa1d4f@oss.qualcomm.com> Content-Language: en-US From: Konrad Dybcio In-Reply-To: <20260905-shutdown-v5-1-f0c6bafa1d4f@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=KP1qylFo c=1 sm=1 tr=0 ts=6aa139fa cx=c_pps a=50t2pK5VMbmlHzFWWp8p/g==:117 a=PRfkaYvzSr8QmIIGAkY2Sg==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=yx91gb_oNiZeI1HMLzn7:22 a=EUspDBNiAAAA:8 a=BuD4T0Y0vivPUdseitkA:9 a=QEXdDO2ut3YA:10 a=IoWCM6iH3mJn3m4BftBB:22 X-Proofpoint-ORIG-GUID: _wxXUoqD9WwWQM2yxST1Jl0zp-j8p1oh X-Proofpoint-Spam-Info: AW1haW4tMjYwOTA5MDEyMCBTYWx0ZWRfX44JtlVTLMsqP xOT91Zw8M8a3udv0LJzr9A26/H1l/0FrdvpyOiHPkLbOjrnFK/IwiGyeCINrmnYhw5BBcByz5nL a0TO60lXvLpxC6hefz3X2xX++gKCRm8= X-Proofpoint-GUID: _wxXUoqD9WwWQM2yxST1Jl0zp-j8p1oh X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTA5MDEyMCBTYWx0ZWRfX7I5BuuBTkBLb JebKLDbE6SarnFnj4270JdykV01ypREjoUvsvvjsDycgd1QlWwwfCPi6jRcp1DQHbhC1MCTF/M7 7pYzVR7SEGkjI0rcwis4TqgBvjjNnxKxjwBYrqOQkeZvMlMPrkIx0uly6RUsg124qieYOrUDR25 1r8plrLG6CQmz4vqjSVomhu14biWbEHV75dGbGDb985OfrMVkE5w37lWL028/G9zCUpLHrTOJKN xbqTlp8nH3/+A0Ij9eJ7jdPD6+WStgcHzDUNH3Xp1BOPscE+jIVOhVGKyed3tndbwr7xpsXDKW8 iMs5lI5LAR9+pooatF0i/qf7BbkfZM7q0//JeQj/ETFISRUSRpduZPOCOLtGyqXU1dfDfGBBSGt nHbp6u/67JmrFDf6SBtc7aSMqoCd75FAhlHrNETXr+8DZQVlwe574gvKgULi8HRML95qiZ8abO9 fzqmE2BB+pvfydrFo7g== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-08_03,2026-09-08_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 lowpriorityscore=0 adultscore=0 spamscore=0 malwarescore=0 suspectscore=0 impostorscore=0 bulkscore=0 priorityscore=1501 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2609090120 On 9/5/26 2:48 AM, Krishna Chaitanya Chundru wrote: > __pci_host_common_d3cold_possible() returns -EOPNOTSUPP for the first > downstream device it finds outside PCI_D3hot, and pci_walk_bus() aborts > the walk as soon as its callback returns nonzero. Any device enumerated > after the disqualifying one -- including a wakeup-enabled, PME-from-D3cold > capable endpoint -- is then never visited, so pme_capable can come back > false even though such a device exists on the bus. > > Since pci_host_common_d3cold_possible() already returns false whenever > any device disqualifies D3cold, aborting the walk buys nothing for the > plain suspend path: the overall bool result is unaffected. But it > silently drops pme_capable detection for any device ordered after the > disqualifying one. > > This matters for the upcoming shutdown path in particular: unlike plain > suspend, shutdown forces the link into L2/D3cold regardless of whether > pci_host_common_d3cold_possible() itself allows it (see the following > "force_d3cold" changes), so at shutdown time it's common for an > endpoint to still be in D0 and disqualify D3cold while a later, > PME-capable device is never visited. dw_pcie_suspend_noirq() still > uses "pme_capable" to set pci->pp.skip_pwrctrl_off, so an inaccurate > result here can cause Vaux/wakeup support to be dropped for a device > that actually supports PME from D3cold. > > Signed-off-by: Krishna Chaitanya Chundru > --- > drivers/pci/controller/pci-host-common.c | 17 +++++++---------- > 1 file changed, 7 insertions(+), 10 deletions(-) > > diff --git a/drivers/pci/controller/pci-host-common.c b/drivers/pci/controller/pci-host-common.c > index a23907a875e5..78bc4c8c9656 100644 > --- a/drivers/pci/controller/pci-host-common.c > +++ b/drivers/pci/controller/pci-host-common.c > @@ -274,22 +274,19 @@ static int __pci_host_common_d3cold_possible(struct pci_dev *pdev, > if (!pdev->dev.driver && !pci_is_enabled(pdev)) > return 0; > > - if (pdev->current_state != PCI_D3hot) > - goto exit; > + if (pdev->current_state != PCI_D3hot) { > + *flags &= ~PCI_HOST_D3COLD_ALLOWED; > + return 0; > + } The way I read the commit message, this return shouldn't be here Konrad > > if (device_may_wakeup(&pdev->dev)) { > - if (!pci_pme_capable(pdev, PCI_D3cold)) > - goto exit; > - else > + if (pci_pme_capable(pdev, PCI_D3cold)) > *flags |= PCI_HOST_PME_D3COLD_CAPABLE; > + else > + *flags &= ~PCI_HOST_D3COLD_ALLOWED; > } > > return 0; > - > -exit: > - *flags &= ~PCI_HOST_D3COLD_ALLOWED; > - > - return -EOPNOTSUPP; > } > > /** >