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

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Message-ID: <20240727072603.GB2974@thinkpad>
Date: Sat, 27 Jul 2024 12:56:03 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Hsin-Yi Wang <hsinyi@...omium.org>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	lukas@...ner.de, mika.westerberg@...ux.intel.com,
	Bjorn Helgaas <helgaas@...nel.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>
Subject: Re: [PATCH v4 0/4] PCI: Allow D3Hot for PCI bridges in Devicetree
 based platforms

On Fri, Jul 26, 2024 at 04:06:03PM -0700, Hsin-Yi Wang wrote:
> On Fri, Jul 26, 2024 at 4:02 PM Manivannan Sadhasivam
> <manivannan.sadhasivam@...aro.org> 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 a lot for testing. I will respin the series once 6.11-rc1 is out.

- Mani

> Thanks!
> 
> > - Mani
> >
> > > - Mani
> > >
> > > [1] https://lore.kernel.org/linux-pci/20240214-pcie-qcom-bridge-v3-1-3a713bbc1fd7@linaro.org/
> > > [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@linaro.org/
> > >
> > > 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@linaro.org
> > >
> > > 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@linaro.org
> > >
> > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > > ---
> > > 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@...aro.org>
> > >
> >
> > --
> > மணிவண்ணன் சதாசிவம்

-- 
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