raspberrypi/linux — pull request #72 by Himmele (2012-08-01 11:40:46+00:00)
Title: Fixed latency issue caused by disabling preemption for up to 5 seconds

Setting up the timeout to 5000 by the RPi patch in sdhci_send_command (sdhci.c) is not a good idea.
This blocks everything on the Raspberry Pi for up to 200ms in real world scenarios.
I don't know if my supplied patch if perfectly correct, but it works for my low latency streaming app.