Re: [PATCH v3 1/3] firmware: xilinx: Add support to clear TF-A PM state

On Fri, Jul 24, 2026 at 03:19:46AM -0700, Jay Buddhabhatti wrote:

Currently, during a kexec restart, only the kernel is reloaded, while the
TF-A specific data remain unchanged. This leads to a mismatch between the
kernel state and the TF-A firmware state like SGI number and shutdown
scope variable.

Avoid using TF-A in general as it can be any other firmware as well.
You can always generalise as PSCI or EL3 firmware.

For example, the kernel registers an SGI number with TF-A so that TF-A can
notify the kernel of events via that SGI. TF-A stores this SGI number in
its internal state. After a kexec, the newly loaded kernel re-registers
and may request a different SGI number, but the stale value programmed in
TF-A remains, so event notifications are delivered on the old SGI and are
missed by the new kernel. The shutdown scope variable has a similar stale
state problem.

Doesn't it reset it every time CPU_OFF or CPU_ON is called ?

To resolve this, the TF_A_CLEAR_PM_STATE PM API is introduced to clear
TF-A-specific state during kexec. On a graceful reboot, this API is
triggered by zynqmp_firmware_shutdown(), while in a crash kernel scenario,
it is invoked by zynqmp_firmware_probe() in the reloaded kernel.

I don't see the need for such an API just for kexec needs. You must deal
with it as part of CPU_ON as it should start with clean slate as SGIs are
per CPU, no ?

-- 
Regards,
Sudeep