I'm planning to do some realtime control loop tasks with the RPi. In this post PREEMPT_RT and Xenomai were proposed. I'm thinking about trying PREEMPT_RT, as I'd like to keep it as simple as possible.
In the linked post, @Nakedible opposes that the current (as of his writing from Sep 29 '12) drivers are a work-in-progress and might still contain long blocking sleeps.
Is this still the case, or are the drivers real-time capable already? I'll need I2C and maybe SPI drivers.