Re: [PATCH v2 0/4] Deterministic SPI latency with NXP DSPI driver

2019-09-09 Thread Vladimir Oltean
Hi Mark, On 09/09/2019, Mark Brown wrote: > On Thu, Sep 05, 2019 at 04:01:10AM +0300, Vladimir Oltean wrote: > >> This patchset proposes an interface from the SPI subsystem for >> software timestamping SPI transfers. There is a default implementation >> provided in the core, as well as a mechanis

Re: [PATCH v2 0/4] Deterministic SPI latency with NXP DSPI driver

2019-09-09 Thread Mark Brown
On Thu, Sep 05, 2019 at 04:01:10AM +0300, Vladimir Oltean wrote: > This patchset proposes an interface from the SPI subsystem for > software timestamping SPI transfers. There is a default implementation > provided in the core, as well as a mechanism for SPI slave drivers to > check which byte was

[PATCH v2 0/4] Deterministic SPI latency with NXP DSPI driver

2019-09-04 Thread Vladimir Oltean
Since v1, I noticed that under CPU load, the pre-to-post delay gets reduced to half (i.e. the code runs twice as fast). After a bit of debugging, turns out this is the effect of the 'ondemand' governor. Disabling dynamic frequency scaling (either by switching to the 'performance' governor or by mak