On Wed, Aug 27, 2014 at 11:35 AM, Nishanth Menon <nm@xxxxxx> wrote: > On Wed, Aug 27, 2014 at 1:27 PM, Kevin Hilman > <khilman@xxxxxxxxxxxxxxxxxxx> wrote: >> Nishanth Menon <nm@xxxxxx> 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@xxxxxx> >>> 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@xxxxxx> >>> --- >> >> 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.. WARN, pr_warn() as you like. The point is that BUG* calls panic() and locks up the system tight. As what your'e adding is not fatal to the entire system, you should not be using bug. From asm-generic/bug.h: * * Don't use BUG() or BUG_ON() unless there's really no way out; one * example might be detecting data structure corruption in the middle * of an operation that can't be backed out of. If the (sub)system * can somehow continue operating, perhaps with reduced functionality, * it's probably not BUG-worthy. * * If you're tempted to BUG(), think again: is completely giving up * really the *only* solution? There are usually better options, where * users don't need to reboot ASAP and can mostly shut down cleanly. */ -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
