* Stephen Boyd <sboyd@xxxxxxxxxxxxxx> [161028 16:37]: > On 10/28, Tony Lindgren wrote: > > * Tero Kristo <t-kristo@xxxxxx> [161028 00:43]: > > > On 28/10/16 03:50, Stephen Boyd wrote: > > > > I suppose a PRCM is > > > > like an MFD that has clocks and resets under it? On other > > > > platforms we've combined that all into one node and just had > > > > #clock-cells and #reset-cells in that node. Is there any reason > > > > we can't do that here? > > > > > > For OMAPs, there are typically multiple instances of the PRCM around; OMAP4 > > > for example has: > > > > > > cm1 @ 0x4a004000 (clocks + clockdomains) > > > cm2 @ 0x4a008000 (clocks + clockdomains) > > > prm @ 0x4a306000 (few clocks + resets + power state handling) > > > scrm @ 0x4a30a000 (few external clocks + plenty of misc stuff) > > > > > > These instances are also under different power/voltage domains which means > > > their PM behavior is different. > > > > > > The idea behind having a clockdomain as a provider was mostly to have the > > > topology visible : prcm-instance -> clockdomain -> clocks > > > > Yeah that's needed to get the interconnect hierarchy right for > > genpd :) > > > > > ... but basically I think it would be possible to drop the clockdomain > > > representation and just mark the prcm-instance as a clock provider. Tony, > > > any thoughts on that? > > > > No let's not drop the clockdomains as those will be needed when we > > move things into proper hierarchy within the interconnect instances. > > This will then help with getting things right with genpd. > > > > In the long run we just want to specify clockdomain and the offset of > > the clock instance within the clockdomain in the dts files. > > > > Sorry, I have very little idea how OMAP hardware works. Do you > mean that you will have different nodes for each clockdomain so > that genpd can map 1:1 to the node in dts? But in hardware > there's a prcm that allows us to control many clock domains > through register read/writes? How is the interconnect involved? There are multiple clockdomains, at least one for each interconnect instance. Once a clockdomain is idle, the related interconnect can idle too. So yeah genpd pretty much maps 1:1 with the clockdomains. There's more info in for example omap4 TRM section "3.4.1 Device Power-Management Layout" that shows the voltage/power/clock domains. The interconnect instances are mostly named there too looking at the L4/L3 naming. Regards, Tony -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
