On Wed, Apr 11, 2012 at 03:53:30PM -0600, Paul Walmsley wrote: > Hi > > On Wed, 11 Apr 2012, Mark A. Greer wrote: > > > From: "Mark A. Greer" <mgreer@xxxxxxxxxxxxxxx> > > > > The am35x family of SoCs only support PWRSTS_ON > > and PWRSTS_INACTIVE states so create a new set > > of powerdomain structures that ensure that only > > the ON and INACTIVE states are entered. > > I'm still unsure what we should do about this INACTIVE state. As far as I > can tell, it does not actually represent a distinct powerdomain state on > OMAP3. We can't write it to the PM_PWSTCTRL_*.POWERSTATE bits, since that > value is marked as "reserved". And SPRUGR0B, the AM3517/3505 TRM, > explicitly states "This register should not be programmed with reserved > values of bit fields for proper functioning of power state control." > Of course SPRUGR0B also claims that AM3517/3505 supports RETENTION, so > that is relatively confusing. Yep. You read one section which tells you the device doesn't support such-and-such then it goes on for pages describing how it works. I play with the hardware and the registers are there so it seems like it should work. Its been an "adventure". :) > OMAP4 PRCM actually does seem to support powerdomain INACTIVE state, > although it does not actually seem to represent a separate state. As I > understand it, it simply allows the clockdomains in the powerdomain to > transitioning from the ACTIVE state into the INACTIVE state. In other > words, it doesn't affect the powerdomain power state at all. And on OMAP4 > it's referred to as the ON-INACTIVE state, to clarify that it is simply a > variant of the ON state. I wish they had just added a separate bit for > this; it would have avoided some frustration... > > Anyway, my question is this: is there any point at all to defining the > INACTIVE state for 3517/3505, given that it apparently cannot be read > from, nor written to the PRCM hardware? Great question and I really don't know the answer--its too hard to know what's for real and what isn't in the TRM. Maybe it is best to get rid of INACTIVE and just leave everything ON. Mark -- -- 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
