Re: [PATCH 3/4] firmware: xilinx: Clear firmware notifiers across kexec transitions

["Pandey, Radhey Shyam" <radheys@amd.com>]

On 7/23/2026 6:18 PM, Jay Buddhabhatti wrote:
> During a kexec restart, only the kernel is reloaded but notifier callbacks
> in firmware persist, causing state mismatches between kernel and firmware.
> 
> To address this, introduce PM_ALL_NOTIFIERS node ID to unregister all
> notifier callbacks during kexec. On a graceful kexec restart, this occurs
> in zynqmp_firmware_shutdown(). On a crash kernel restart, it happens in
> zynqmp_firmware_probe() in the reloaded kernel.
> 
> Unregistering all notifiers depends on firmware support for the
> PM_ALL_NOTIFIERS node ID. On firmware that does not implement it (the
> feature check reports a version below PM_API_VERSION_3) the step is
> skipped and a warning such as "Firmware doesn't support unregister all
> notifiers at once" is logged, e.g. on Versal NET firmware that predates
> this API.
> 
> Signed-off-by: Jay Buddhabhatti <jay.buddhabhatti@amd.com>

Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
Thanks!

> ---
>   drivers/firmware/xilinx/zynqmp.c     | 14 ++++++++++++++
>   include/linux/firmware/xlnx-zynqmp.h |  3 +++
>   2 files changed, 17 insertions(+)
> 
> diff --git a/drivers/firmware/xilinx/zynqmp.c b/drivers/firmware/xilinx/zynqmp.c
> index 64d2109eefd2..fc7212f554ee 100644
> --- a/drivers/firmware/xilinx/zynqmp.c
> +++ b/drivers/firmware/xilinx/zynqmp.c
> @@ -2110,6 +2110,20 @@ static int zynqmp_clear_pm_state(struct device *dev)
>   				 "Bulk device release is not supported by firmware: %d\n", ret);
>   			ret = 0;
>   		}
> +
> +		/* Check if the firmware supports the PM_ALL_NOTIFIERS node ID */
> +		ret = do_feature_check_call(PM_REGISTER_NOTIFIER);
> +		if (ret >= 0 && ((ret & FIRMWARE_VERSION_MASK) >= PM_API_VERSION_3)) {
> +			/* Attempt to unregister all notifier callbacks via firmware */
> +			ret = zynqmp_pm_register_notifier(PM_ALL_NOTIFIERS, 0, 0, 0);
> +			if (ret)
> +				dev_err(dev, "Failed to unregister all notifiers: %d\n", ret);
> +		} else {
> +			dev_warn(dev,
> +				 "Firmware doesn't support unregister all notifiers at once: %d\n",
> +				 ret);
> +			ret = 0;
> +		}
>   	}
>   
>   	return ret;
> diff --git a/include/linux/firmware/xlnx-zynqmp.h b/include/linux/firmware/xlnx-zynqmp.h
> index ac39e5492961..69a2f74269f3 100644
> --- a/include/linux/firmware/xlnx-zynqmp.h
> +++ b/include/linux/firmware/xlnx-zynqmp.h
> @@ -149,6 +149,9 @@
>   /* Node ID for all peripheral devices */
>   #define PM_DEV_ALL_PERIPH	0x18224FFFU
>   
> +/* Node ID for all notifier callbacks */
> +#define PM_ALL_NOTIFIERS	0xFFFFFFFFU
> +
>   enum pm_module_id {
>   	PM_MODULE_ID = 0x0,
>   	XPM_MODULE_ID = 0x2,