Re: [PATCH 08/13] OMAP3: PM: Deny MPU idle while saving secure RAM

[Nishanth Menon <nm@ti.com>]

Kevin Hilman had written, on 11/19/2010 01:41 PM, the following:

>>> I believe the fix we are attempting here is for a specific scenario
>>> which IMHO is different from the issue solved in the link above.
>> It will also solve the above issue indirectly.
> 
> Yes, it indirectly fixes the issue solved by $SUBJECT patch, but what
> else does it fix?
Please see [1] - highlights:
a) I dont seem to understand how clock domain idle is being denied by 
the patch
b) the mentioned patch[1] should have removed the pwr_domain control 
around the secure ram operation - which is the only weakness in that 
patch, for power domain control, I like the mentioned patch - but 
pwrdomain control is not what is being introduced here.

> 
> This secure mode call is currently the only one I'm aware of that does a
> WFI.  If there are others, then $SUBJECT patch is not enough. 
> 
> If TI cannot tell us definitively if other secure-mode calls may use
> WFI, then we have to assume there are others, and $SUBJECT patch has to
> be NAK'd in favor of a more generic fix like the one from Santosh.
Thanks on the unfair beating IMHO, but, I believe I confirmed this 
here[2] - Quote: "After a long review, the impacted section is this 
logic alone." if you do have other specific SMIs in doubt(the ones we 
have verified to my knowledge are the ones around sleep34xx code), 
please list them out and I can get confirmation on behalf of TI if WFI 
is in use or not. AFAIK, SMIs can be supported by ROMcode and by PPA. is 
WFI is being used by PPA - there is no guarantee on the custom 
implementations.
For example:
CONFIG_OMAP3_L2_AUX_SECURE_SAVE_RESTORE -> has a service ID which could 
be implemented by PPA -> TI cannot guarentee that implementations will 
never use WFI, from a kernel context, we'd say - dont use wfi - let the 
kernel control it, though the actual implementation is upto the 
developer of PPA.

Ref:
[1]http://marc.info/?l=linux-omap&m=129019267128364&w=2
[2] http://marc.info/?l=linux-omap&m=129018700620594&w=2

-- 
Regards,
Nishanth Menon