+ Tomi,
On 7/9/2011 3:25 PM, Paul Walmsley wrote:
Hi
On Mon, 9 May 2011, sricharan wrote:
Paul Walmsley reported a kernel hang issue with beagle board
during boot. This is an intermittent bug and the execution was
found to be stuck at the l3 interrupt handler.
This was due to a dss initiator agent timeout occuring during the
boot even when there is no actual interconnect access made by the
dss. since the reason for the dss timeout is not root caused yet,
the time out feature is disabled at the interconnect level. Note
that this is a temporary fix that should be removed once the dss
interconnect agent timeout issue is resolved.
So it's been two months since this bug was reported. Any progress
on root-causing it?
I don't see how I can upstream this temporary patch with a straight
face.
Sorry for not closing the loop on this thread but I thought Tomi
root-caused the DSS timeout issue to incorrect reset sequence of
DSS IP. With that fixed I though we shouldn't see that issue.
First, it tries to unconditionally reset the L3 DSS interconnect
agent, even if there's no problem on the L3 DSS IA that requires a
reset. It should only try to reset an IA if it's in a bad state.
This was to ensure that the issue hasn't happened during boot-loader
DSS reset sequence in case it does. But I agree with your comments.
Second, are you sure that reset sequence is correct? Writing a 1 and
then a 0 to that reset bit, without any barrier or delay in between?
Could you please confirm that this is a correct reset sequence with
the L3 IA designers and cc me on the E-mails, or send me an extract
from the relevant documentation?
Third, the patch disables L3 timeout reporting. This effectively
reacts to an error by pretending that the error did not exist. This
isn't right. If there's an L3 timeout, it needs to be reported, if at
all possible. It should never happen and it indicates something is
wrong with the software or the hardware.
Will come back to you on above queries.
Regards
Santosh
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