Re: [PATCH v2 4/8] PCI: Change the parent to correctly represent pcie hierarchy

Manivannan Sadhasivam
2024-08-23T07:23:47Z

On Sat, Aug 03, 2024 at 08:52:50AM +0530, Krishna chaitanya chundru wrote:
> Currently the pwrctl driver is child of pci-pci bridge driver,
> this will cause issue when suspend resume is introduced in the pwr
> control driver. If the supply is removed to the endpoint in the
> power control driver then the config space access by the
> pci-pci bridge driver can cause issues like Timeouts.
>
> For this reason change the parent to controller from pci-pci bridge.
>

Also, what if the PCIe controller driver tries to access the device? Like for
sending PME_Turn_Off etc... during suspend? I think you should also make sure
that the suspend callback of the pwrctl driver has to happen _after_ the
controller driver.

Still the parent-child hierarchy is not going to change, but only the devlink
part.

- Mani

> Fixes: 4565d2652a37 ("PCI/pwrctl: Add PCI power control core code")
> Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
> ---
> drivers/pci/bus.c | 3 ++-
> drivers/pci/pwrctl/core.c | 9 ++++++++-
> 2 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
> index 55c853686051..15b42f0f588f 100644
> --- a/drivers/pci/bus.c
> +++ b/drivers/pci/bus.c
> @@ -328,6 +328,7 @@ void __weak pcibios_bus_add_device(struct pci_dev *pdev) { }
> */
> void pci_bus_add_device(struct pci_dev *dev)
> {
> + struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
> struct device_node *dn = dev->dev.of_node;
> int retval;
>
> @@ -352,7 +353,7 @@ void pci_bus_add_device(struct pci_dev *dev)
>
> if (dev_of_node(&dev->dev) && pci_is_bridge(dev)) {
> retval = of_platform_populate(dev_of_node(&dev->dev), NULL, NULL,
> - &dev->dev);
> + host->dev.parent);
> if (retval)
> pci_err(dev, "failed to populate child OF nodes (%d)\n",
> retval);
> diff --git a/drivers/pci/pwrctl/core.c b/drivers/pci/pwrctl/core.c
> index feca26ad2f6a..4f2ffa0b0a5f 100644
> --- a/drivers/pci/pwrctl/core.c
> +++ b/drivers/pci/pwrctl/core.c
> @@ -11,6 +11,8 @@
> #include <linux/property.h>
> #include <linux/slab.h>
>
> +#include "../pci.h"
> +
> static int pci_pwrctl_notify(struct notifier_block *nb, unsigned long action,
> void *data)
> {
> @@ -64,18 +66,23 @@ static int pci_pwrctl_notify(struct notifier_block *nb, unsigned long action,
> */
> int pci_pwrctl_device_set_ready(struct pci_pwrctl *pwrctl)
> {
> + struct pci_bus *bus;
> int ret;
>
> if (!pwrctl->dev)
> return -ENODEV;
>
> + bus = pci_find_bus(of_get_pci_domain_nr(pwrctl->dev->parent->of_node), 0);
> + if (!bus)
> + return -ENODEV;
> +
> pwrctl->nb.notifier_call = pci_pwrctl_notify;
> ret = bus_register_notifier(&pci_bus_type, &pwrctl->nb);
> if (ret)
> return ret;
>
> pci_lock_rescan_remove();
> - pci_rescan_bus(to_pci_dev(pwrctl->dev->parent)->bus);
> + pci_rescan_bus(bus);
> pci_unlock_rescan_remove();
>
> return 0;
>
> --
> 2.34.1
>

--
மணிவண்ணன் சதாசிவம்