On Tue, Nov 17, 2020 at 11:54:17AM +0100, Ahmad Fatoum wrote: > Hello William, > > On 06.11.20 13:42, William Breathitt Gray wrote: > > On Thu, Nov 05, 2020 at 07:46:14PM +0100, Ahmad Fatoum wrote: > >> It doesn't look like the counter device API is yet made to support such > >> an input capture mode (latching a counter value on an external event, e.g. > >> to timestamp incoming rising edges to measure jitter between pulses). > > > > Regarding the Counter subsystem, I'm developing a Counter character > > device API that supports timestamps for counter devices: > > https://lore.kernel.org/linux-arm-kernel/157d1edf-feec-33b5-7ad5-94f99316ca6e@xxxxxxxxxxxxxx/T/ > > Any chance we could have a "raw" timestamp as well like the network > stack offers (cf. SOF_TIMESTAMPING_{RAW,SYS}_HARDWARE)? > > The API currently only exposes a ktime (i.e. CLOCK_MONOTONIC), which the > raw timer count can't be readily converted to. For our use case of > measuring jitter, the raw value is sufficient. Sure, we can add support for a "raw" timestamp. I can see how this could be more useful in certain circumstances rather than the ktime value. I'll open a discussion about it when I submit the next revision of the Counter character device patchset. :-) William Breathitt Gray
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