On Fri, 14 Apr 2023 at 07:55, Maulik Shah <quic_mkshah@xxxxxxxxxxx> wrote:
>
> A switch from OSI to PC mode is only possible if all CPUs other than the
> calling one are OFF, either through a call to CPU_OFF or not yet booted.
>
> Currently OSI mode is enabled before power domains are created. In cases
> where CPUidle states are not using hierarchical CPU topology the bail out
> path tries to switch back to PC mode which gets denied by firmware since
> other CPUs are online at this point and creates inconsistent state as
> firmware is in OSI mode and Linux in PC mode.
>
> This change moves enabling OSI mode after power domains are created,
> this would makes sure that hierarchical CPU topology is used before
> switching firmware to OSI mode.
>
> Fixes: 70c179b49870 ("cpuidle: psci: Allow PM domain to be initialized even if no OSI mode")
> Signed-off-by: Maulik Shah <quic_mkshah@xxxxxxxxxxx>
> ---
> drivers/cpuidle/cpuidle-psci-domain.c | 37 +++++++++------------------
> 1 file changed, 12 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/cpuidle/cpuidle-psci-domain.c b/drivers/cpuidle/cpuidle-psci-domain.c
> index c2d6d9c3c930..c3993df24eef 100644
> --- a/drivers/cpuidle/cpuidle-psci-domain.c
> +++ b/drivers/cpuidle/cpuidle-psci-domain.c
> @@ -120,20 +120,6 @@ static void psci_pd_remove(void)
> }
> }
>
> -static bool psci_pd_try_set_osi_mode(void)
> -{
> - int ret;
> -
> - if (!psci_has_osi_support())
> - return false;
> -
> - ret = psci_set_osi_mode(true);
> - if (ret)
> - return false;
> -
> - return true;
> -}
> -
> static void psci_cpuidle_domain_sync_state(struct device *dev)
> {
> /*
> @@ -152,15 +138,12 @@ static int psci_cpuidle_domain_probe(struct platform_device *pdev)
> {
> struct device_node *np = pdev->dev.of_node;
> struct device_node *node;
> - bool use_osi;
> + bool use_osi = psci_has_osi_support();
> int ret = 0, pd_count = 0;
>
> if (!np)
> return -ENODEV;
>
> - /* If OSI mode is supported, let's try to enable it. */
> - use_osi = psci_pd_try_set_osi_mode();
> -
> /*
> * Parse child nodes for the "#power-domain-cells" property and
> * initialize a genpd/genpd-of-provider pair when it's found.
> @@ -178,25 +161,29 @@ static int psci_cpuidle_domain_probe(struct platform_device *pdev)
>
> /* Bail out if not using the hierarchical CPU topology. */
> if (!pd_count)
> - goto no_pd;
> + goto remove_pd;
We should return 0 here instead, right?
>
> /* Link genpd masters/subdomains to model the CPU topology. */
> ret = dt_idle_pd_init_topology(np);
> if (ret)
> - goto remove_pd;
> + goto remove_pd_topology;
This looks wrong to me. Shouldn't we continue to goto the "remove_pd"
label for this error path?
> +
> + /* let's try to enable OSI. */
> + ret = psci_set_osi_mode(use_osi);
> + if (ret)
> + goto remove_pd_topology;
>
> pr_info("Initialized CPU PM domain topology using %s mode\n",
> use_osi ? "OSI" : "PC");
> return 0;
>
> -put_node:
> - of_node_put(node);
> +remove_pd_topology:
> + dt_idle_pd_remove_topology(np);
> remove_pd:
> psci_pd_remove();
> +put_node:
> + of_node_put(node);
This of_node_put() should only be called if we break the
"for_each_child_of_node" loop above because of an error, I think.
Perhaps it's cleaner to just move this within the loop?
> pr_err("failed to create CPU PM domains ret=%d\n", ret);
> -no_pd:
> - if (use_osi)
> - psci_set_osi_mode(false);
> return ret;
> }
>
Kind regards
Uffe
