Re: [PATCH v3] firmware: stratix10-svc: add PSCI secondary CPU offline on warm reboot for agilex and stratix10

[Dinh Nguyen <dinguyen@kernel.org>]

On 9/4/26 00:52, Adrian Ng Ho Yin wrote:
> On Agilex7 and Stratix10 SoCs, secondary CPUs must be offlined before
> a warm reboot to ensure a clean PSCI state. Agilex5 warm reset is a
> SDM-owned HPS reset that holds secondaries in the new reset-release until
> ATF releases them, so the secondary cores dont have to be put offline
> first. Register a reboot notifier that calls remove_cpu() on each
> secondary CPU when SYS_RESTART is triggered in REBOOT_WARM mode.
> 
> A snapshot of cpu_online_mask is taken before the loop since remove_cpu()
> modifies the mask as CPUs go down. CPU 0 is excluded as it is typically
> not hotpluggable. Failures are logged and the loop continues so the
> reboot is not blocked by a single CPU that refuses to offline.
> The of_device_id table carries a per-compatible pdata flag to enable the
> notifier only on platforms that need it; Agilex5 leaves the flag unset.
> 
> The notifier is unregistered at the start of remove(), before async
> channel teardown, to prevent a reboot notification from racing with
> driver shutdown.
> 
> Signed-off-by: Adrian Ng Ho Yin <adrian.ho.yin.ng@altera.com>
> ---
> changelog:
> v2 -> v3:
> - Use ctrl in psci_offline_secondary_cpus() via dev_err(ctrl->dev, ...)
>    instead of pr_err(). The controller pointer was unused; this both
>    consumes it and attributes the failure to the svc device.
> - Keep of_device_id.data / stratix10_svc_pdata rather than dropping it
>    because both intel,stratix10-svc and intel,agilex-svc happen to share
>    the same notifier path. A separate patch adds intel,agilex5-svc without
>    .data so Agilex5 does not run this sequence. Agilex5 warm reset is an
>    SDM-owned HPS reset (REBOOT_HPS) that holds secondaries in the
>    reset-release / P-channel block until ATF CPURSTRELEASE; Linux must
>    not PSCI-offline them first.
> 
> v1 -> v2:
> - Drop workqueue fan-out: remove_cpu() serialises on device_hotplug_lock
>    internally so concurrent workers provided no parallelism. Replace with
>    a single sequential loop over a cpumask snapshot.
> - Fix CPU identity bug: get_cpu()/put_cpu() did not prevent task migration
>    and the notifier can run on any CPU before migrate_to_reboot_cpu().
>    Exclude CPU 0 (typically not hotpluggable) and offline everything else.
> - Fix pre-count race: the two-loop atomic pre-count had a window where a
>    concurrent hotplug event could cause dec_and_test() to fire prematurely.
>    Eliminated entirely along with the completion and timeout.
> - Replace of_device_is_compatible() checks with a stratix10_svc_pdata
>    struct carried in of_device_id.data, retrieved via of_device_get_match_data().
> - Move psci_cpu_off_teardown() to the top of stratix10_svc_drv_remove(),
>    before async channel teardown, to close the race where a warm-reboot
>    notification could fire while the driver is being dismantled.
> 
> ---
>   drivers/firmware/stratix10-svc.c | 88 ++++++++++++++++++++++++++++++--
>   1 file changed, 85 insertions(+), 3 deletions(-)
> 
I had some erros apply this patch, but was able to finally do it. Please 
double-check the applied patch on my branch: socfpga_firmware_for_v7.4

Dinh