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

[Kevin Hilman <khilman@ti.com>]

"Menon, Nishanth" <nm@ti.com> writes:

> On Wed, Feb 15, 2012 at 09:20, Kevin Hilman <khilman@ti.com> wrote:
>> Tero Kristo <t-kristo@ti.com> writes:
>>
>>> On Tue, 2012-02-14 at 15:52 -0800, Tony Lindgren wrote:
>>>> * Kevin Hilman <khilman@ti.com> [120214 14:28]:
>>>> > Tony Lindgren <tony@atomide.com> writes:
>>>> >
>>>> > > * Tero Kristo <t-kristo@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

Yes, although that is targetted pretty narrowly at suspend and only PRM
registers.

Do you then use omapconf to display the results?

Kevin