[PATCH 6/6] arm: omap: pm-debug: enhanced usecount debug support

[Menon, Nishanth]

On Wed, Feb 15, 2012 at 09:20, Kevin Hilman <khilman at ti.com> wrote:
> Tero Kristo <t-kristo at ti.com> writes:
>
>> On Tue, 2012-02-14 at 15:52 -0800, Tony Lindgren wrote:
>>> * Kevin Hilman <khilman at ti.com> [120214 14:28]:
>>> > Tony Lindgren <tony at atomide.com> writes:
>>> >
>>> > > * Tero Kristo <t-kristo at ti.com> [120214 08:19]:
>>> > >> Voltdm, pwrdm, clkdm, hwmod and clk usecounts are now separeted to
>>> > >> their own file, 'usecount'. This file shows the usecounts for every
>>> > >> active domain and their children recursively. 'count' file now only
>>> > >> shows power state counts for powerdomains.
>>> > >>
>>> > >> This patch also provices a way to do printk dumps from kernel code,
>>> > >> by calling the pm_dbg_dump_X functions. The plan is to call these
>>> > >> functions once an error condition is detected, e.g. failed suspend.
>>> > >
>>> > > Why don't you replace this all with a userspace tool that deciphers
>>> > > the registers for you?
>>> >
>>> > This patch isn't deciphering registers, it's just dumping usecounts, and
>>> > I think that is extremely useful to have in debugfs.
>>> >
>>> > I've already removed all the register dumping from the kernel in the
>>> > hopes that someone will write a userspace tool for that.
>>>
>>> OK good to hear you're already considering it.
>>
>> Yes, register dumps are gone, and I am actually one of the persons who
>> is missing it.
>>
>> I think there should still be some capability to get register snapshots
>> from certain points during kernel execution, this is useful for
>> debugging purposes. I don't know if it would be possible to do a
>> call_usermodehelper() or something from kernel space just before wfi to
>> read all (or part of) the PRCM registers, store them somewhere, and then
>> decipher this data later with another tool. Any comments to this?
>
> You should look into the omapconf tool (TI internal only currently)
>
> This tool already has the ability to use /dev/mem to read/decipher OMAP
> PM related registers.
>
> IMO, the one thing we're still missing is the ability to take register
> snapshots (like immediately before and after WFI) and somehow feed those
> to omapconf for deciphering.
>
Something like this perhaps?
https://github.com/nmenon/linux-omap-ti-pm/commit/3cd1994fc0df9a8e3e0be74ec3f3add3ff3aef95

Regards,
Nishanth Menon