Colin,
On Friday 22 July 2011 10:51 AM, Colin Cross wrote:
On Thu, Jul 21, 2011 at 10:10 PM, Santosh Shilimkar
[....]
For my OMAP4 PM rebasing, for time-being I will go with exported
GIC functions so that I don't have too many redundancies with GIC
save/restore code.
I think you should try to balance cpu idle latency with reuse of
common code. In this case, you are avoiding restoring 7 registers by
reimplementing the bare minimum that is necessary for OMAP4, which is
unlikely to make a measurable impact on wakeup latency. Can you try
starting with reusing all the common code, and add some timestamps
during wakeup to measure where the longest delays are, to determine
where you should diverge from the common code and use omap-optimized
code?
I am going to use all the common code but having them exported
functions gives more flexibility to call them in right and needed
places. As discussed earlier, I plan to use the common GIC code
wherever it's needed on OMAP.
My main point was we are saving and restoring GIC CPU interface
registers for a case where they are actually not lost.
Yes, but you're still avoiding 7 registers, which is unlikely to be
worth the complexity of calling these functions differently from every
other platform.
I managed to use pm notifiers for GIC and VFP on OMAP4 and
get that working. As discussed here, I decided to take the
hit on the latency in favour of re-use of the code for GIC
considering it's helping other platforms.
I did update notifiers patches for couple of things.
- VFP code now make use 'vfp_current_hw_state' instead of
'last_VFP_context'
- I have renamed CPU_COMPLEX to more appropriate CPU_CLUSTER
- I have dropped GIC dist. disable as part of GIC dist save
code. I saw lock ups with CPUIDLE and then tracked down, to
an issue where for some reason if cluster doesn't hit the
targeted low power state, CPU gets locked up since GIC
dist. remains disabled. The GIC restore is done only if
the cluster did hit the deeper state and GIC lost it's
context. As such this change should not impact anything.
What's your plan on these notifiers patches considering
there is a request to make them generic and not just ARM
specific?
Sorry for asking this but now I have dependency on this
series :)
If you want, I can participate here to get this moving.
Let me know.
Regards
Santosh
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