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

Nishanth Menon nm at ti.com
Wed Aug 27 11:35:46 PDT 2014

On Wed, Aug 27, 2014 at 1:27 PM, Kevin Hilman
<khilman at deeprootsystems.com> wrote:
> Nishanth Menon <nm at 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 at 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 at 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",
         return PWRDM_POWER_ON;

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

Nishanth Menon

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