Re: [PATCH v5 0/3] pps: improve PREEMPT_RT performance

[Michael Byczkowski]

Hi Sebastian,

Thanks very much for the review.

On 22 May 2026, at 16:13, Sebastian Andrzej Siewior wrote:
> Was there a follow-up to the series?

Yes: v6 is on the way. Calvin Owens kindly offered to relay it for
me (Apple Mail has been corrupting my patches in transit; I'm
addressing that separately), so the v6 series will arrive from him
shortly.

A summary of how I've addressed your v5 comments:

1/3 (pps-gpio handler split): commit message reworded. The new
   message describes the split structurally first -- primary hardirq
   handler that captures the timestamp, threaded handler that
   processes the event -- and then describes the PREEMPT_RT benefit
   second (no more scheduling delay between IRQ entry and timestamp
   capture). The patch itself is unchanged.

2/3 (pps_kc_hardpps_lock -> raw_spinlock_t): I'd appreciate a quick
   clarification here. You wrote that pps_kc_hardpps_lock "is
   spinlock_t in my tree". My patch is against mainline at
   0d9363a764d9 ("Input: xpad - add support for BETOP BTP-KP50B/C
   controller's wireless mode"), where it is still DEFINE_SPINLOCK.
   Could you point me at the branch you were looking at, so I can
   check whether v6 needs to rebase on top of an existing conversion
   in your tree?

   Separately: I've also taken your suggestion and refactored
   pps_kc_bind() (and pps_kc_remove() while I was in the file) to use
   guard(raw_spinlock_irq). That eliminates the four duplicated unlock
   call sites in pps_kc_bind() and removes the ambiguous bracket
   nesting. Thank you for that pointer.

3/3 (pps_device.lock -> raw_spinlock_t): reordered so this comes
   after the kc_hardpps conversion (which now becomes patch 2/3 in
   v6), as you noted -- the previous ordering would briefly produce
   a raw_spinlock holding a sleeping spinlock on PREEMPT_RT. Thank
   you for catching that.

Also: thank you for auditing pps_gpio_echo() on my behalf, much
appreciated.

Best regards,
	Michael