The interrupt handling of the sc16is7xx driver is broken in a number of ways, as observed by multiple Raspberry Pi users. The attached patches attempt to address its failings, with apparent success.
The first is a workaround for a side-effect of the switch away from using a thread IRQ, a change which has necessitated using what is actually a level-triggered interrupt as if it were edge-triggered. Doing so is fraught with potential race conditions, but the patch makes them much less likely. The second is a workaround for a bug in the design of the SC16IS752 which requires mutual exclusion between the interrupt handler and access to the Enhanced Features Register. Phil Elwell (2): sc16is7xx: Fix for multi-channel stall sc16is7xx: Fix for "Unexpected interrupt: 8" drivers/tty/serial/sc16is7xx.c | 50 +++++++++++++++++++++++++++++++++++++----- 1 file changed, 44 insertions(+), 6 deletions(-) -- 2.7.4
