OMAP baseline test results for v3.7-rc1

Felipe Balbi balbi at
Tue Oct 30 08:54:19 EDT 2012


On Tue, Oct 30, 2012 at 12:50:52PM +0000, Paul Walmsley wrote:
> On Tue, 30 Oct 2012, Felipe Balbi wrote:
> > the wmb() patch should help, but you said it doesn't, right ?
> Correct.  Not sure why you think that would help; the problem is almost 

because of how the driver is behaving...

The only way for omap_i2c_wait_for_bb() to timeout is if the bus is
really still busy; meaning that either transfer hasn't fully completed
(some data still in FIFO), or we didn't send STOP or Repeated START
condition on the bus.

> 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 ?

> > without seeing debugging information on the failing case, it'll be very
> > difficult to sort this one out provided noone else seems to be able to
> > reproduce it.
> Aaro sees it also, so it's definitely not a local artifact.

Again I don't doubt it.

> It's not very surprising that the problem doesn't appear with the extra 
> logging enabled, since the extra logging presumably keeps the system out 
> of idle.  
> Anyway, you are welcome to the userspace, bootloader, and X-loader here if 
> you would like to try to reproduce it.  They've been sent to Jean and 
> Kevin and Shubhrajyoti already.  Simply request it and I will send links.

I can have a look, sure, but I don't have the same platform as you have.
I have a beagle XM revB (according to the stickers on the board) which I
could use to try to reproduce, if I manage to, then hooray :-)

In that case, please give me also a link to your uImage so I can make
sure to use the exact same setup.


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