Re: [PATCH v4 7/9] OMAP3: PM: Adding debug support to Voltage and Smartreflex drivers

[Nishanth Menon <nm@ti.com>]

Gopinath, Thara had written, on 12/08/2010 10:18 AM, the following:
[..]
>>> And, AFAICT, it wasn't clear from the current code or docs whether this
>>> could work or was expected to work either, e.g., if you set
>>> override_volt_params back to zero, to the original values all get reused?
>>>
>>> If you want to provide this feature, then it should be documented and
>>> made clear that this is an intended goal.
>>>
>>> Thinking about this more, the main thing I don't like about this
>>> approach is that the active code paths (enable & disable) have to check
>>> each time if any of these values have been overidden.
>>>
>>> Rather than have several places in the active code paths where this
>>> override value is checked, there the sysfs methods should simply update
>>> the values that are used by the core code.  This way, the core would
>>> not need to know about where the values came from (defalts, volt_data,
>>> user override, etc.)
>>>
>>> If you want to provide a way to revert this, then maybe writing -1 will
>>> should switch that value back to the HW default, or volt_data default.
> Kevin, Benoit, Nishant et al,
> 
> Without this override flag today there is no direct way of
> allowing user to write into these parameters. My question is,
Glancing at the debug entries being overidden, as developer (debug 
users) working for tweaking parameters for their platform - yes - we 
will need some mechanism to runtime tweak and see the behavior without 
needing to rebuild the kernel everytime.

On production system (OS users): they should'nt be using this.


> is there a need for the parameters to be over-written
> from the user-space? If yes, I need ideas on how to
> implement it with using override_volt_params !

Lets get the basics in kernel.org in some form! IMHO, all this double 
knobs are un-necessary overheads in codeflow for development only code- 
just provide the debugfs entries that reflect the data in their original 
structures, use the original structures everytime we go to a new 
transition (aka if you change the params in debugfs, they dont take 
effect till you do another transition).. but that is just my 2cents.

---
Regards,
Nishanth Menon