On Sat, Aug 03, 2024 at 08:52:46AM GMT, 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. This is not a proper changelog entry. It doesn't allow reviewers to understand what actually happened. Could you please list your actual changes in a reply and also include them in a changelog if there is a need for v3. > - 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/ > --- > -- With best wishes Dmitry
