[PM] 25/08/10 - Minutes for the Power Management WG weekly call

Amit Kucheria amit.kucheria at linaro.org
Wed Aug 25 10:41:15 BST 2010

The minutes of the weekly call can be found at:


The minutes and actions are copied below.



Linaro: Amit Kucheria, Amit Arora, Yong Shen
ARM: Robin Randhawa, Bobby Batacharia, Srinivas Kalaga

== Action Items from this Meeting ==
 * ACTION: Yong to work with John Rigby and Ubuntu kernel team to make sure the Linaro kernel contains powertop kernel patches
 * ACTION: Vishwa to verify powertop on 2.6.35
 * ACTION: Vishwa to check with cpuidle/cpufreq experts in TI for verifying cpufreq behavior on multi-core OMAP
 * ACTION: Amit A to get the powertop patch integrated into Linaro/Ubuntu packages
 * ACTION: Yong to test common clk API patches on imx5 and help get it booting on babbage 3.0
== Action Items from Previous Meeting ==

 * ACTIVE (Immediate):  
   * ACTION: Amit A to test on pm enabled OMAP3 board: DONE on 2.6.32 on zoom3 board
     * New ACTION: Vishwa to verify on 2.6.35
   * ACTION: Amit A to document details on power supply class (battery info) to PowerTOP internal wiki page: DONE
   * ACTION: Yong to look into getting powertop kernel patches applied to Linaro kernel tree: Not DONE
     * New ACTION: Yong to work with John Rigby and make sure the Linaro kernel contains it
   * ACTION: Robin to send links to patches sent to linux-pm: DONE
     * http://www.spinics.net/lists/cpufreq/msg01740.html
     * It was a pointer to a discussion on having different governors on different cores
   * ACTION: Amit K to spend some time on usecase to reproduce ondemand governor problems: POSTPONED
   * ACTION: Yong to look at common clock FW, find out if debug info being exported (usage count, clk rate, dependencies): DONE

 * DORMANT :  
  * ACTION: ARM to share  internal  instrumentation flow (BAB: we might also align with Linaro on workload discussions)  
     * Might take couple of months   
  * ACTION: Amit K to talk to jeremy about power domain framework: DONE
     * Jeremy needs help, will revisit in a few weeks
  * ACTION: Srinivas to provide details of where he believes userspace - kernel interaction is required. (low prio)  
  * ACTION: Bobby to check on multi-core boards availability (request open)  
  * ACTION: ARM to discuss giving out internal Eclipse based tool (similar to powertop)  (no ETA as of now)   
  * ACTION: Amit Kucheria and Vishwa to get inputs from community on the issues related to CPUIDLE governor: POSTPONED until instrumentation work 

== Minutes ==
  * Discussion on http://www.spinics.net/lists/cpufreq/msg01740.html
    * For ARM, both cores run at same frequency (CMP)
      * Does it make sense for them to run different governors on each core?
        * The consensus currently is NO
    * TI uses ondemand governor + policy manager
      * One core is kept OFF, all processing happens on the other one.
      * If load on one core goes above a threshold, they turn ON other core
      * Both cores run at same Operating Point once ON
  * Debug info in common clk API being discussed upstream by Jeremy
    * There is currently no debug info
    * clock name is not part of the common struct clk to keep size down
    * Need to engage with Jeremy
    * Yong will test the patches from Jeremy on imx5 and report back
  * Powerdebug: should we visualise the clock and power dependencies using information from /sys or debugfs?
    * No immediate horror expressed at the idea
    * Freescale and TI already do it to a certain extent by dumping the clock tree and rates into a table
    * The entire tree is too complex to depict
    * We could represent it in parts e.g. start at a peripheral and plot it's clock and power dependencies all the way up

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