Re: [PATCH v4 0/4] PCI: Allow D3Hot for PCI bridges in Devicetree based platforms

From: Manivannan Sadhasivam
Date: Sat May 11 2024 - 03:15:51 EST


On Tue, Mar 26, 2024 at 04:18:16PM +0530, Manivannan Sadhasivam wrote:
> Hi,
>
> This series allows D3Hot for PCI bridges in Devicetree based platforms.
> Even though most of the bridges in Devicetree platforms support D3Hot, PCI
> core will allow D3Hot only when one of the following conditions are met:
>
> 1. Platform is ACPI based
> 2. Thunderbolt controller is used
> 3. pcie_port_pm=force passed in cmdline
>
> While options 1 and 2 do not apply to most of the DT based platforms,
> option 3 will make the life harder for distro maintainers.
>
> Initially, I tried to fix this issue by using a Devicetree property [1], but
> that was rejected by Bjorn and it was concluded that D3Hot should be allowed by
> default for all the Devicetree based platforms.
>
> During the review of v3 series, Bjorn noted several shortcomings of the
> pci_bridge_d3_possible() API [2] and I tried to address them in this series as
> well.
>
> But please note that the patches 2 and 3 needs closer review from ACPI and x86
> folks since I've splitted the D3Hot and D3Cold handling based on my little
> understanding of the code.
>
> Testing
> =======
>
> This series is tested on SM8450 based development board on top of [3].
>

Bjorn, a gently ping on this series.

- Mani

> - Mani
>
> [1] https://lore.kernel.org/linux-pci/20240214-pcie-qcom-bridge-v3-1-3a713bbc1fd7@xxxxxxxxxx/
> [2] https://lore.kernel.org/linux-pci/20240305175107.GA539676@bhelgaas/
> [3] https://lore.kernel.org/linux-arm-msm/20240321-pcie-qcom-bridge-dts-v2-0-1eb790c53e43@xxxxxxxxxx/
>
> Changes in v4:
> - Added pci_bridge_d3_possible() rework based on comments from Bjorn
> - Got rid of the DT property and allowed D3Hot by default on all DT platforms
>
> Changes in v3:
> - Fixed kdoc, used of_property_present() and dev_of_node() (Lukas)
> - Link to v2: https://lore.kernel.org/r/20240214-pcie-qcom-bridge-v2-1-9dd6dbb1b817@xxxxxxxxxx
>
> Changes in v2:
> - Switched to DT based approach as suggested by Lukas.
> - Link to v1: https://lore.kernel.org/r/20240202-pcie-qcom-bridge-v1-0-46d7789836c0@xxxxxxxxxx
>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> ---
> Manivannan Sadhasivam (4):
> PCI/portdrv: Make use of pci_dev::bridge_d3 for checking the D3 possibility
> PCI: Rename pci_bridge_d3_possible() to pci_bridge_d3_allowed()
> PCI: Decouple D3Hot and D3Cold handling for bridges
> PCI: Allow PCI bridges to go to D3Hot on all Devicetree based platforms
>
> drivers/pci/bus.c | 2 +-
> drivers/pci/pci-acpi.c | 9 ++---
> drivers/pci/pci-sysfs.c | 2 +-
> drivers/pci/pci.c | 90 ++++++++++++++++++++++++++++++++--------------
> drivers/pci/pci.h | 12 ++++---
> drivers/pci/pcie/portdrv.c | 16 ++++-----
> drivers/pci/remove.c | 2 +-
> include/linux/pci.h | 3 +-
> 8 files changed, 89 insertions(+), 47 deletions(-)
> ---
> base-commit: 705c1da8fa4816fb0159b5602fef1df5946a3ee2
> change-id: 20240320-pci-bridge-d3-092e2beac438
>
> Best regards,
> --
> Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
>

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