Re: [PATCH v7 1/1] pps: pps-gpio: split IRQ handler into hardirq timestamper + threaded handler

[Michael Byczkowski]

Thank you Sebastian, and thank you Calvin for relaying. I appreciate the
thorough review that got this to the right shape.

Best regards,
	Michael


> On 2. Jun 2026, at 08:36, Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote:
> 
> On 2026-06-01 17:44:09 [-0700], Calvin Owens wrote:
>> From: Michael Byczkowski <by@xxxxxxxxxxxx>
>> 
>> Split the pps-gpio interrupt handler into a primary (hardirq) handler
>> that captures the PPS timestamp at interrupt entry, and a threaded
>> handler that processes the event. This produces the same two-part
>> handler structure on both PREEMPT_RT and non-RT kernels.
>> 
>> On non-RT kernels the threaded portion runs immediately after the
>> primary, with no behavioral change compared to the previous
>> single-handler implementation.
>> 
>> On PREEMPT_RT, where interrupt handlers are force-threaded by default,
>> the previous single-handler implementation captured the timestamp
>> inside the threaded portion, after IRQ-thread scheduling delay. With
>> the split, the timestamp is captured in true hardirq context as it is
>> on non-RT kernels, eliminating a significant source of PPS jitter on
>> RT systems.
>> 
>> Tested-by: Michael Byczkowski <by@xxxxxxxxxxxx>
>> Tested-by: Calvin Owens <calvin@xxxxxxxxxx>
>> Acked-by: Rodolfo Giometti <giometti@xxxxxxxxxxxx>
>> Signed-off-by: Michael Byczkowski <by@xxxxxxxxxxxx>
>> Signed-off-by: Calvin Owens <calvin@xxxxxxxxxx>
>> ---
> 
> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> 
> Sebastian