[dmaengine] [Q] jiffies value does not increase in dma_sync_wait()

From: javier Martin
Date: Fri Feb 03 2012 - 03:37:48 EST

I have a Visstrim_M10 board, based on i.MX27, and I'm developing a
v4l2 driver for deinterlacing video frames.

Whenever I start a new dma transfer I call the function
"dma_wait_for_async_tx()" which internally ends up calling


In this function, there is a "do while" loop, which checks for dma
completion, with a timeout. However, when the system is too loaded
this function enters this "do while" loop and never gets out of it,
blocking the system.

I've introduced a couple of printk() to check why this timeout is not
triggered and I've found that the value of jiffies does not increase
between loop iterations (i. e. it's like time didn't advance).

Does anyobody know what reasons could make jiffies not being updated?

Javier Martin
Vista Silicon S.L.
CDTUC - FASE C - Oficina S-345
Avda de los Castros s/n
39005- Santander. Cantabria. Spain
+34 942 25 32 60
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/