Hello, Minor suggestion. On Fri, May 18, 2012 at 01:18:41PM -0500, ext Nishanth Menon wrote: > From: Wenbiao Wang <wwang@xxxxxx> > > Voltage Processor state machine transition to disable need to > occur from IDLE state. When we transition OPP in a functioning > system, the call sequence for an OPP transition is as follows: > omap_sr_disable > -> sr class 3 disable > -> vp disable > -> sr disable > forceupdate to voltage/frequency scale depending on which OPP > we are transitioning to. > > If we hit a critical timing window where SR had commanded VP > for a voltage transition and VP is in the middle of operating > on that command, it needs to go through a few states before > going to update state(where it actually sends the command to > VC). Initial view of h/w owners is that the state disable of VP > is expected to be sampled for the next transition. > > Instead, to be on a safer side, we ensure that the valid states > of the VP state machine is diligently followed by software. This > can be done by waiting for VP to be in idle prior to disabling > VP. Existing prints have been updated to ensure context is > available on error messages. > > As part of this change, increase timeout for VP idle check to > improbable 500uSec to be certain that system is indeed unable > to continue before crashing out with error(worst case expectancy > remains the same 3-100uSec depending on when we caught VP). > <cut> > > /* XXX document */ > -#define VP_IDLE_TIMEOUT 200 > +#define VP_IDLE_TIMEOUT 500 I guess it is time to properly document this increasing busy loop delay.. As it is getting closer to ms scale.. > #define VP_TRANXDONE_TIMEOUT 300 > > /** > -- > 1.7.9.5 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- 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
