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

[Hsin-Yi Wang]

On Fri, Jul 26, 2024 at 4:02 PM Manivannan Sadhasivam
<manivannan.sadhasivam@xxxxxxxxxx> wrote:
>
> 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.
>

Hi, I was also working on a similar patch to add bridge_d3 to arm
platforms until I found this series, which is what we need. Also
kindly ping on this series.

Thanks!

> - 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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