Hi, I’m using a linux-wandboard-rt 3.14.28, with a max latency of 114us [1]. I would like include an IIO driver to acquire data from a SPI device @ 1Hz. After disable some modules (as suggested two months ago by Mat and tglx [2]) the acquisition is more stable, however it still losing data. Based on a scope and a couple of GPIO, I could find that the SPI handler is not firing sometimes. I don’t understand why the max latency (with cyclictest is 114us) and the SPI handler @1ms is failing with delays of 3 to 5ms. There is a way to force the SPI handler over all others kernel process? This could be related with the priority of the SPI (spi0)? In this case the thread spi0 has PRI of 20 with a nice of 0 [3]. Do you suggest to continuing digging to find the cause in other modules? Thanks Julio ----- [1] cyclictest result cyclictest -t1 -p 80 -n -i 1000 -l 100000 # /dev/cpu_dma_latency set to 0us policy: fifo: loadavg: 0.11 0.25 0.14 1/94 549 T: 0 ( 548) P:80 I:1000 C: 100000 Min: 10 Act: 15 Avg: 15 Max: 114 ----- [2] [2015-09-26 9:38:02] Long max latencies on Wandbaord / Freescale i.MX6 ----- [3] htop and system modules: http://postimg.org/image/jrvcw5v59/-- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
