Documentation/power/opp.rst

5 (C) 2009-2010 Nishanth Menon <nm@ti.com>, Texas Instruments Incorporated
20 -------------------------------------------------
22 Complex SoCs of today consists of a multiple sub-modules working in conjunction.
25 facilitate this, sub-modules in a SoC are grouped into domains, allowing some
27 voltage/frequency pairs that are higher.
41 - {300000000, 1000000}
42 - {800000000, 1200000}
43 - {1000000000, 1300000}
46 ----------------------------------------
57  (users)	-> registers a set of default OPPs		-> (library)
58  SoC framework	-> modifies on required cases certain OPPs	-> OPP layer
59 		-> queries to search/retrieve information	->
73 SoC framework might choose to disable a higher frequency OPP to safely continue
74 operations until that OPP could be re-enabled if possible.
96 optimally- typical numbers range to be less than 5. The list generated by
146 	higher frequency could be made available, it can use this function to
178 	higher match OR operating on OPP information in the order of increasing
186 	Example 2: A simplified implementation of a SoC cpufreq_driver->target::
216 	SoC temperature is lower than a certain threshold. The SoC framework
233 	exceeds a threshold value. The SoC framework implementation might
293 			 return -EINVAL;
295 			 return -EINVAL;
301 	Example: Lets say a co-processor in the SoC needs to know the available
329    |- device 1
330    |	|- opp 1 (availability, freq, voltage)
331    |	|- opp 2 ..
333    |	`- opp n ..
334    |- device 2
336    `- device m
366               +-----+        /- dev_pm_opp_enable
367   dev_pm_opp_add --> | opp | <-------
368     |         +-----+        \- dev_pm_opp_disable
369     \-------> domain_info(device)
372                /-- dev_pm_opp_find_freq_ceil  ---\   +-----+
373   domain_info<---- dev_pm_opp_find_freq_exact -----> | opp |
374                \-- dev_pm_opp_find_freq_floor ---/   +-----+
377   +-----+     /- dev_pm_opp_get_voltage
378   | opp | <---
379   +-----+     \- dev_pm_opp_get_freq
381   domain_info <- dev_pm_opp_get_opp_count