Re: [PATCH 4/7] ARM: OMAP2+: powerdomain: introduce logic for finding valid power domain

Nishanth Menon
2014-08-27T18:35:48Z

On Wed, Aug 27, 2014 at 1:27 PM, Kevin Hilman
<khilman@deeprootsystems.com> wrote:
> Nishanth Menon <nm@ti.com> writes:
>
>> powerdomain configuration in OMAP is done using PWRSTCTRL register for
>> each power domain. However, PRCM lets us write any value we'd like to
>> the logic and power domain target states, however the SoC integration
>> tends to actually function only at a few discrete states. These valid
>> states are already in our powerdomains_xxx_data.c file.
>>
>> So, provide a function to easily query valid low power state that the
>> power domain is allowed to go to.
>>
>> Based on work originally done by Jean Pihet <j-pihet@ti.com>
>> https://patchwork.kernel.org/patch/1325091/ . There is no attempt to
>> create a new powerdomain solution here, except fixing issues seen
>> attempting invalid programming attempts. Future consolidation to the
>> generic powerdomain framework should consider this requirement as
>> well.
>>
>> Similar solutions have been done in product kernels in the past such
>> as:
>> https://android.googlesource.com/kernel/omap.git/+blame/android-omap-panda-3.0/arch/arm/mach-omap2/pm44xx.c
>>
>> Signed-off-by: Nishanth Menon <nm@ti.com>
>> ---
>
> nit: this is part of a fixes series, but it's more of a new feature.
>
> That being said, the feature is needed and looks OK, except for...
>
>> +up_search:
>> + /* OK, no deeper ones, can we get a higher match? */
>> + new_pwrst = req_state + 1;
>> + while (!(pwrdm_states & BIT(new_pwrst))) {
>> + /* BUG if we have messed up database */
>> + BUG_ON(new_pwrst > PWRDM_POWER_ON);
>
> I don't think this is BUG() worthy, and should have a saner way to recover.

it is not even a legal value to have a power state higher than ON. I
mean, yeah, we can do
if (new_pwrst > PWRDM_POWER_ON) {
pr_debug("powerdomain: %s: fix my powerdomain max to ON\n",
pwrdm->name);
return PWRDM_POWER_ON;
}

if that is your suggestion here, personally, I would use a WARN at least here..

--
---
Regards,
Nishanth Menon