On Tue, 30 Oct 2012, Felipe Balbi wrote:

On Tue, Oct 30, 2012 at 12:50:52PM +0000, Paul Walmsley wrote:

quoted

certainly PM-idle related, given that the problem goes away by reverting 
Jean's commit 3db11feffc1ad2ab9dea27789e6b5b3032827adc "ARM: OMAP: convert 
I2C driver to PM QoS for MPU latency constraints".

The problem is consistent and easy to reproduce here.

I don't doubt that :-) What I think, however, is that PM QoS just made
the problem a bit easier to trigger for whatever reason. Maybe because
pm qos defers constraint updates, or something similar ?

Based on a very quick look, I'd say the original patch 3db11fe is broken.  
I don't see how it can ensure that its PM_QOS_CPU_DMA_LATENCY request is 
honored when CONFIG_CPU_IDLE=n. CONFIG_CPU_IDLE=n is the default for 
omap2plus_defconfig.


- Paul