CyanogenMod/android_kernel_motorola_omap4-common — pull request #2 by dtrail (2013-07-20 22:56:39+00:00)
Title: omap: serial: disable serial port irq during suspend 

If the serial port interrupt is left enabled during suspend, it
can fire during uart_resume_port, while the uart is in an
undefined state and the port lock is not held.

Disable the interrupt in serial_omap_suspend, and enable it in
serial_omap_resume. This also requires moving the request_irq
into probe, instead of startup, so that the irq is always
available to disable.

This will save additional power in idle mode/deep sleep. It has beend tested and after this patch we had a better idle line e.g. in Battery Monitor Widget.