Re: [PATCH v2 0/8] PCI: Enable Power and configure the QPS615 PCIe switch

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





On 8/3/2024 8:52 AM, Krishna chaitanya chundru wrote:
QPS615 is the PCIe switch which has one upstream and three downstream
ports. One of the downstream ports is used as endpoint device of Ethernet
MAC. Other two downstream ports are supposed to connect to external
device. One Host can connect to QPS615 by upstream port.

QPS615 switch power is controlled by the GPIO's. After powering on
the switch will immediately participate in the link training. if the
host is also ready by that time PCIe link will established.

The QPS615 needs to configured certain parameters like de-emphasis,
disable unused port etc before link is established.

The device tree properties are parsed per node under pci-pci bridge in the
devicetree. Each node has unique bdf value in the reg property, driver
uses this bdf to differentiate ports, as there are certain i2c writes to
select particulat port.
As the controller starts link training before the probe of pwrctl driver,
the PCIe link may come up before configuring the switch itself.
To avoid this introduce two functions in pci_ops to start_link() &
stop_link() which will disable the link training if the PCIe link is
not up yet.

Now PCI pwrctl device is the child of the pci-pcie bridge, if we want
to enable the suspend resume for pwrctl device there may be issues
since pci bridge will try to access some registers in the config which
may cause timeouts or Un clocked access as the power can be removed in
the suspend of pwrctl driver.

To solve this make PCIe controller as parent to the pci pwr ctrl driver
and create devlink between host bridge and pci pwrctl driver so that
pci pwrctl driver will go suspend only after all the PCIe devices went
to suspend.

Signed-off-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>
---
Changes in V1:
- Fix the code as per the comments given.
changes in v1:
- Instead of referencing whole i2c-bus add i2c-client node and reference it (Dmitry)
- Change the regulator's as per the schematics as per offline review
(bjorn Andresson)
- Remove additional host check in bus.c (Bart)
- For stop_link op change return type from int to void (Bart)
- Remove firmware based approach for configuring sequence as suggested
by multiple reviewers.
- Introduce new dt-properties for the switch to configure the switch
as we are replacing the firmware based approach.
- The downstream ports add properties in the child nodes which will
represented in PCIe hierarchy format.
- Removed D3cold D0 sequence in suspend resume for now as it needs
separate discussion.

- Krishna Chaitanya.
- Removed D3cold D0 sequence in suspend resume for now as it needs
   seperate discussion.
- change to dt approach for configuring the switch instead of request_firmware() approach
- Link to v1: https://lore.kernel.org/linux-pci/20240626-qps615-v1-4-2ade7bd91e02@xxxxxxxxxxx/T/
---

---
Krishna chaitanya chundru (8):
       dt-bindings: PCI: Add binding for qps615
       dt-bindings: trivial-devices: Add qcom,qps615
       arm64: dts: qcom: qcs6490-rb3gen2: Add node for qps615
       PCI: Change the parent to correctly represent pcie hierarchy
       PCI: Add new start_link() & stop_link function ops
       PCI: dwc: Add support for new pci function op
       PCI: qcom: Add support for host_stop_link() & host_start_link()
       PCI: pwrctl: Add power control driver for qps615

  .../devicetree/bindings/pci/qcom,qps615.yaml       | 191 ++++++
  .../devicetree/bindings/trivial-devices.yaml       |   2 +
  arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts       | 121 ++++
  arch/arm64/boot/dts/qcom/sc7280.dtsi               |   2 +-
  drivers/pci/bus.c                                  |   3 +-
  drivers/pci/controller/dwc/pcie-designware-host.c  |  18 +
  drivers/pci/controller/dwc/pcie-designware.h       |  16 +
  drivers/pci/controller/dwc/pcie-qcom.c             |  39 ++
  drivers/pci/pwrctl/Kconfig                         |   7 +
  drivers/pci/pwrctl/Makefile                        |   1 +
  drivers/pci/pwrctl/core.c                          |   9 +-
  drivers/pci/pwrctl/pci-pwrctl-qps615.c             | 638 +++++++++++++++++++++
  include/linux/pci.h                                |   2 +
  13 files changed, 1046 insertions(+), 3 deletions(-)
---
base-commit: 1722389b0d863056d78287a120a1d6cadb8d4f7b
change-id: 20240727-qps615-e2894a38d36f

Best regards,




[Index of Archives]     [DMA Engine]     [Linux Coverity]     [Linux USB]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Greybus]

  Powered by Linux