Re: [PATCH 0/9] PCI: introduce the concept of power sequencing of PCIe devices

[Neil Armstrong <neil.armstrong@linaro.org>]

On 17/01/2024 17:07, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> 
> The responses to the RFC were rather positive so here's a proper series.
> 
> During last year's Linux Plumbers we had several discussions centered
> around the need to power-on PCI devices before they can be detected on
> the bus.
> 
> The consensus during the conference was that we need to introduce a
> class of "PCI slot drivers" that would handle the power-sequencing.
> 
> After some additional brain-storming with Manivannan and the realization
> that DT maintainers won't like adding any "fake" nodes not representing
> actual devices, we decided to reuse existing PCI infrastructure.
> 
> The general idea is to instantiate platform devices for child nodes of
> the PCIe port DT node. For those nodes for which a power-sequencing
> driver exists, we bind it and let it probe. The driver then triggers a
> rescan of the PCI bus with the aim of detecting the now powered-on
> device. The device will consume the same DT node as the platform,
> power-sequencing device. We use device links to make the latter become
> the parent of the former.
> 
> The main advantage of this approach is not modifying the existing DT in
> any way and especially not adding any "fake" platform devices.
> 
> Changes since RFC:
> - move the pwrseq functionality out of the port driver and into PCI core
> - add support for WCN7850 to the first pwrseq driver (and update bindings)
> - describe the WLAN modules in sm8550-qrd and sm8650-qrd
> - rework Kconfig options, drop the defconfig changes from the series as
>    they are no longer needed
> - drop the dt-binding changes for PCI vendor codes
> - extend the DT bindings for ath11k_pci with strict property checking
> - various minor tweaks and fixes
> 
> Bartosz Golaszewski (7):
>    arm64: dts: qcom: qrb5165-rb5: describe the WLAN module of QCA6390
>    PCI: create platform devices for child OF nodes of the port node
>    PCI: hold the rescan mutex when scanning for the first time
>    PCI/pwrseq: add pwrseq core code
>    dt-bindings: wireless: ath11k: describe QCA6390
>    dt-bindings: wireless: ath11k: describe WCN7850
>    PCI/pwrseq: add a pwrseq driver for QCA6390
> 
> Neil Armstrong (2):
>    arm64: dts: qcom: sm8550-qrd: add Wifi nodes
>    arm64: dts: qcom: sm8650-qrd: add Wifi nodes
> 
>   .../net/wireless/qcom,ath11k-pci.yaml         |  89 ++++++
>   arch/arm64/boot/dts/qcom/qrb5165-rb5.dts      |  29 ++
>   arch/arm64/boot/dts/qcom/sm8250.dtsi          |  10 +
>   arch/arm64/boot/dts/qcom/sm8550-qrd.dts       |  37 +++
>   arch/arm64/boot/dts/qcom/sm8550.dtsi          |  10 +
>   arch/arm64/boot/dts/qcom/sm8650-qrd.dts       |  29 ++
>   arch/arm64/boot/dts/qcom/sm8650.dtsi          |  10 +
>   drivers/pci/Kconfig                           |   1 +
>   drivers/pci/Makefile                          |   1 +
>   drivers/pci/bus.c                             |   9 +-
>   drivers/pci/probe.c                           |   2 +
>   drivers/pci/pwrseq/Kconfig                    |  16 ++
>   drivers/pci/pwrseq/Makefile                   |   4 +
>   drivers/pci/pwrseq/pci-pwrseq-qca6390.c       | 267 ++++++++++++++++++
>   drivers/pci/pwrseq/pwrseq.c                   |  82 ++++++
>   drivers/pci/remove.c                          |   3 +-
>   include/linux/pci-pwrseq.h                    |  24 ++
>   17 files changed, 621 insertions(+), 2 deletions(-)
>   create mode 100644 drivers/pci/pwrseq/Kconfig
>   create mode 100644 drivers/pci/pwrseq/Makefile
>   create mode 100644 drivers/pci/pwrseq/pci-pwrseq-qca6390.c
>   create mode 100644 drivers/pci/pwrseq/pwrseq.c
>   create mode 100644 include/linux/pci-pwrseq.h
> 

Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8550-QRD
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD

Thanks,
Neil