Re: [RFC PATCH 0/5] Arm LFA: Improvements and interrupt support

[Vedashree Vidwans]

On 12/9/25 03:39, Sudeep Holla wrote:
> On Mon, Dec 08, 2025 at 10:13:10PM +0000, Vedashree Vidwans wrote:
> > Hello,
> >
> > The patches update the proposed Arm Live Firmware Activation (LFA)
> > kernel driver [1] to incorporate review feedback [2] and refine the
> > activation flow while remaining aligned with the LFA specification
> > DEN0147 [3] and the SMCCC 1.2 calling convention. The series keeps
> > the existing functionality but restructures and extends it to improve
> > robustness, reviewability, and future extensibility.​
> >
> > The SMCCC usage in the driver is updated to consistently use the
> > SMCCC 1.2 register-based calling convention, consolidating arguments
> > and results into a single struct to reduce stack usage and simplify
> > the SMC interface. The patches also split the original changes into
> > focused pieces and document the device node bindings in the commit
> > messages, making it easier to follow and validate the implementation
> > against the specification.​
> >
> > The kernel driver is registered as a platform driver in accordence to
> > the LFA device defined by the specification [3]. The driver now extends
> > interface for interrupt-based enablement of LFA. During LFA, the
> > interrupt
> > thread refreshes firmware component details after each activation step
> > and iterates over all activable components until no further activation
> > is pending, matching the spec’s allowance for component detail changes
> > after activation. This ensures that sysfs exposure of LFA components
> > remains consistent with the authoritative information provided by the
> > secure firmware.​
> >
> > The handling of CPU rendezvous is adjusted so that the kernel now
> > honors the rendezvous policy chosen by the firmware, instead of
> > unconditionally forcing a rendezvous. This reflects experience with
> > existing firmware deployments where mandatory rendezvous is not
> > required, while still allowing the firmware to request it when
> > needed.​
> >
> > Thank you,
> > Veda
> >
> > [1] https://lore.kernel.org/lkml/20250926123145.268728-1-salman.nabi@xxxxxxx/
> > [2] https://lkml.org/lkml/2025/10/8/980
> > [3] https://developer.arm.com/documentation/den0147/latest/
> >
> > Vedashree Vidwans (5):
> >    firmware: smccc: LFA: use smcc 1.2
> >    firmware: smccc: LFA: refactor
> >    firmware: smccc: add timeout, touch wdt
> >    firmware: smccc: register as platform driver
> >    firmware: smccc: lfa: refresh fw details
> >
> >   drivers/firmware/smccc/Kconfig  |   3 +-
> >   drivers/firmware/smccc/lfa_fw.c | 478 +++++++++++++++++++++++++-------
>
> Same comment as before[1], looks like the feedback got ignored or missed.
>
> --
> Regards,
> Sudeep
>
> [1]https://lore.kernel.org/all/20251009-calculating-glorious-oriole- 
> ceccf6@sudeepholla

Thank you for your comment.
I did include DT binding in commit message of the patch. Please let me 
know if there's anything else I can elaborate.

Regards,
Veda