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[129.46.96.20]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2b6a49173b2sm293974eec.31.2026.01.14.18.16.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Jan 2026 18:16:24 -0800 (PST) Date: Wed, 14 Jan 2026 18:16:22 -0800 From: Qiang Yu To: Krishna Chaitanya Chundru Cc: Vinod Koul , Neil Armstrong , Philipp Zabel , Jingoo Han , Manivannan Sadhasivam , Lorenzo Pieralisi , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Rob Herring , Bjorn Helgaas , linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org Subject: Re: [PATCH 0/5] PCI: qcom: Add link retention support Message-ID: References: <20260109-link_retain-v1-0-7e6782230f4b@oss.qualcomm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20260109-link_retain-v1-0-7e6782230f4b@oss.qualcomm.com> X-Proofpoint-ORIG-GUID: LpauF4NwT-__16UgP5e_Q35j7dokDoIP X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTE1MDAxMSBTYWx0ZWRfX27SE+grwX+m1 E7sKStKzBux1CaRl8LTH+3sTijECBGZYWewJNdYlOdlJKYmEFmnpL5z2fc1DbZba0ntp2LGWsnl pVI9GVB9fUZV5GHZ1QcNrzru6pW32CH1Mb13VPeWiuxkTmViSsOfOsm6hWo/GICUzrm/BLCMsiK AlQJmnQzowFwqDPLDlFmTjU/Iz1esvYrlKm1KS/vK1HXcALf1bdP5aANC1+8XSQHVZyWYgertDv DyXXmBOtKVMEUSsSYXyN+S5vK0UR4K9o+XbHuL2JZc8RV33XYYdLk76k4v5oy2A+mDx+7ZIWKgu ockyAEGDGvqWcG4SYFeUR7cpbb4Vet1KYT9wf4YcgzY9qcuz1evgR472MqXR/hhPnLsbXQ56SsF PJZRdvu87lEQB1manhnT/rejEqDBwY+BLoSNQLqYme+ol8hv0VANPl2GMSuucXlsof+mHkvmMC/ 9Oojner4Ie35Qv1EiGg== X-Authority-Analysis: v=2.4 cv=W+w1lBWk c=1 sm=1 tr=0 ts=69684dfa cx=c_pps a=PfFC4Oe2JQzmKTvty2cRDw==:117 a=ouPCqIW2jiPt+lZRy3xVPw==:17 a=kj9zAlcOel0A:10 a=vUbySO9Y5rIA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=EUspDBNiAAAA:8 a=ietwBVO8KLLdgrj2ZJ4A:9 a=CjuIK1q_8ugA:10 a=6Ab_bkdmUrQuMsNx7PHu:22 X-Proofpoint-GUID: LpauF4NwT-__16UgP5e_Q35j7dokDoIP X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2026-01-15_01,2026-01-14_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 impostorscore=0 malwarescore=0 spamscore=0 lowpriorityscore=0 clxscore=1015 adultscore=0 suspectscore=0 phishscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2512120000 definitions=main-2601150011 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260114_181628_926294_CD2001E3 X-CRM114-Status: GOOD ( 26.65 ) X-BeenThere: linux-phy@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux Phy Mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-phy" Errors-To: linux-phy-bounces+linux-phy=archiver.kernel.org@lists.infradead.org On Fri, Jan 09, 2026 at 12:51:05PM +0530, Krishna Chaitanya Chundru wrote: > This patch series introduces support for retaining the PCIe link across > bootloader and kernel handoff on Qualcomm platforms, specifically > X1E80100. The goal is to reduce boot time and avoid unnecessary link > reinitialization when the link is already up. > > We are not enabling link retantion support for all the targets, as there > is no guarantee that the bootloader on all targets has initialized the > PCIe link in max supported speed. So we are enabling for hamoa & glymur > target only for now based on the config flag. > > If the link is up and has link_retain is set to true in the > ithe driver config data then enable retain logic in the controller. > > In phy as we already have skip init logic, the phy patch uses same > assumption that if there is phy no csr and bootloader has done the init > then driver can skip resetting the phy when phy status indicates it is > up. > > Problem:- > 1) As part of late init calls of clock & GENPD(for power domains) the > framework is disabling all the unvoted resources by that time and also > there is no sync state to keep them enabled till the probe is completed. > Due to dependencies with regulators and phy, qcom pcie probe is happening > after late init which is causing the resources(clocks & power domains) to > be off which causes the link to go down. To avoid this we need to use these > two kernel command line arguments (clk_ignore_unused & pd_ignore_unused) > to skip disabling clocks and gendp power domains as part of late init > for initial version. Once it is resolved we can avoid those kernel command > line arguments. > > Signed-off-by: Krishna Chaitanya Chundru Tested on Hamoa QCP and Glymur CRD, so Tested-by: Qiang Yu > --- > Krishna Chaitanya Chundru (5): > phy: qcom: qmp-pcie: Skip PHY reset if already up > PCI: dwc: Add support for retaining link during host init > PCI: qcom: Keep PERST# GPIO state as-is during probe > PCI: qcom: Add link retention support > PCI: qcom: enable Link retain logic for Hamoa > > drivers/pci/controller/dwc/pcie-designware-host.c | 11 ++-- > drivers/pci/controller/dwc/pcie-designware.h | 1 + > drivers/pci/controller/dwc/pcie-qcom.c | 62 ++++++++++++++++++++--- > drivers/phy/qualcomm/phy-qcom-qmp-pcie.c | 28 ++++++---- > 4 files changed, 83 insertions(+), 19 deletions(-) > --- > base-commit: fc065cadc7ed048bedbb23cb6b7c4475198f431c > change-id: 20251001-link_retain-f181307947e4 > > Best regards, > -- > Krishna Chaitanya Chundru > > -- linux-phy mailing list linux-phy@lists.infradead.org https://lists.infradead.org/mailman/listinfo/linux-phy