| Message ID | 20230403154922.20704-1-manivannan.sadhasivam@linaro.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | PCI: qcom: Add support for system suspend and resume | expand |
On Mon, 03 Apr 2023 21:19:21 +0530, Manivannan Sadhasivam wrote: > This series (a single patch) adds the system suspend and resume support > to the Qualcomm PCIe RC controller. > > Background > ========== > > There were previous attempts [1][2] to add system suspend and resume > support to this driver. > > [...] Applied to controller/qcom, thanks! [1/1] PCI: qcom: Add support for system suspend and resume https://git.kernel.org/pci/pci/c/ca0e2aad2720 Thanks, Lorenzo
Hello, This series (a single patch) adds the system suspend and resume support to the Qualcomm PCIe RC controller. Background ========== There were previous attempts [1][2] to add system suspend and resume support to this driver. In previous versions, the controller was put into low power mode by turning OFF the resources even if there were active PCIe devices connected. Thanks to Qualcomm's internal power topology, the link did not enter L2/L3 state and the devices were still powered ON. But during very late end of suspend cycle, kernel tried to disable MSIs of the PCIe devices. This caused access violations as the resources needed to access the PCIe devices config space were turned OFF. Series [1] worked around this issue by not accessing the PCIe config space if the link was down in dw_msi_{un}mask_irq() functions. But that approach was not accepted. Then, series [2] implemented the suspend and resume operations using the syscore framework that disabled the resources at the end of the suspend cycle. But that approach also did not get much acceptance. Proposal ======== So the proposal here is to just vote for minimal interconnect bandwidth to keep the interconnect path active and not turn OFF the resources if there are active PCIe devices connected to the controllers. This avoids the access violation issue during suspend and also saves some power due to the lower interconnect bandwidth used. Then if there are no active PCIe devices connected to the controller, the resources are turned OFF completely and brought back during resume. This also saves power if there are controllers in a system without any devices connected. Testing ======= This series has been tested on Lenovo Thinkpad X13s. Thanks, Mani [1] https://lore.kernel.org/linux-pci/1656055682-18817-1-git-send-email-quic_krichai@quicinc.com/ [2] https://lore.kernel.org/linux-pci/1663669347-29308-1-git-send-email-quic_krichai@quicinc.com/ Changes in v4: * Used 1KiB interconnect bandwidth during suspend Changes in v3: * Limited comments to 80 column * Added error handling in resume_noirq() Changes in v2: * Used minimum icc vote to keep data path functional during suspend * Collected Ack Manivannan Sadhasivam (1): PCI: qcom: Add support for system suspend and resume drivers/pci/controller/dwc/pcie-qcom.c | 62 ++++++++++++++++++++++++++ 1 file changed, 62 insertions(+)