SRF Replacement - Constraints Part

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This wikipage describes the efforts of replacing constraints part of the Shared Resource Framework (SRF).
This wikipage describes the efforts of replacing constraints part of the Shared Resource Framework (SRF).
Here is an overview presentation: [[File: Latency_constraint_summary.ppt]]
==SRF Replacement - Constraints Part==
==SRF Replacement - Constraints Part==

Revision as of 18:02, 11 August 2010



This wikipage describes the efforts of replacing constraints part of the Shared Resource Framework (SRF).

Here is an overview presentation: File:Latency constraint summary.ppt

SRF Replacement - Constraints Part

Types of Latency Constraints

Details of Interrupt Latency

Details of Device Latency

Details of throughput constraint

Proposed Implementation

void omap_pm_set_max_dev_wakeup_lat(struct device *dev, long t)
	/*  existing code */	
	1. Look for devices’ power domain (multiple step lookup as starting  with general device)
	2. Use device pointer as identifier for constraint request

	if (t == -1)
		pwrdm_wakeuplat_release_constraint(pwrdm, dev);
		pwrdm_wakeuplat_set_constraint (pwrdm, dev, t);
struct powerdomain {
/* existing entries*/
const u32 wakeuplat[NUM_FUNC_PWRST];
static LIST_HEAD(wakeup_lat_constraint_list);
static struct powerdomain core_44xx_pwrdm = {
.wakeuplat = {
  [FUNC_PWRST_OFF] = 50,
  [FUNC_PWRST_ON] = 0,
pwrdm_wakeuplat_set_constraint (struct powerdomain *pwrdm, stuct device *dev, long lat_us){
	1. If new constraint, add a new entry to wakeup_lat_constraint_list
	2. If already existing, update entries’ latency value
	3. pwrdm_check_for_state_change (pwrdm)
pwrdm_wakeuplat_release_constraint (struct powerdomain *pwrdm, char   *lat_dev_name){
	1. Remove this devices’ constraint from wakeup_lat_constraint_list
	2. pwrdm_check_for_state_change (pwrdm)
pwrdm_wakeuplat_update_pwrst (struct powerdomain *pwrdm){
	1. min_latency = find_min_wakeup_latency_constraint (pwrdm) 
		 //go through the list for minimum latency value
	2. find power state that has latency lower than minimum constraint
	3.  if (pwrdm->state != new_state)
 		    pwrdm_set_next_pwrst (pwrdm, new_state); // existing function to program next state

Implementation Schedule

Post PM Workshop Deliverables for SRF Replacement - Constraints Part

Task Owner Target Date State Status Comments & Actions
Start with the design as aligned in the workshop and implement check for state change function Vibhore 25-Jun Completed 30-Jun: Completed 23-Jun: On track None
Resolve any compilation issues & test on zoom3 Vibhore New: 07-Jul Old: 28-Jun Completed 07-Jul: Faced few issues with test code which had to be developed for testing device latency constraints 02-Jul: debugging & functionality testing 23-Jun: None None
Internally post device latency constraints for review Vibhore New: 19-Jul Old: 12-Jul Completed 19-Jul: Vishwa provided the review comments; 14-Jul: Delayed as Vibhore is on leave 07-Jul: None None
Fix review comments, re-validate & post to LO Vibhore New: 06-Aug Old: 28-Jul Completed 11-Aug: Posted to LO 04-Aug: Posted to PM domain mailing list & fixing review comments received; validation on OMAP4 is limited due to non-availablity of CORE RET & OFF in OMAP4 till now 21-Jul: Revalidation on OMAP3 will be done by 23-Jul and on OMAP4 by 28-Jul None
Validate device latency constraints on OMAP4 & post to LO Vibhore 30-Sep Not started 11-Aug: Patches are there; they need to be validated on OMAP4 once CORE RET & CORE OFF is supported on OMAP4 Depends on availability of CORE RET & CORE OFF functionality on OMAP4
Implement interrupt latency constraints using PM QoS Vishwa New: 21-Jul Old: 15-Jul Completed 21-Jul: Vishwa has completed the implementation 14-Jul: Delayed as Vibhore is on leave 07-Jul: None None
Post RFC patches for interrupt latency Vishwa New: 22-Jul, Old: 19-Jul, 30-Jun Completed 04-Aug: Submitted to L24.9 21-Jul: No major comments expected as the changes are straight forward 07-Jul: Prioritized the device latency constraint implementation which is new 02-Jul: Delayed, 23-Jun: None None
Implement throughput constraints & post RFC patches Shweta New: 13-Aug Old: 06-Aug 30-Jul, 22-Jul In progress 11-Aug: Delayed due more time needed to address the internal review comments received 04-Aug: Posted to internal mailing list; fixing the review comments received. Targeting 06-Aug for posting to LO. Anyway, this feature has a dependency on CORE DVFS 21-Jul: Basic implementation is done; OMAP3 validation targeted for 23-Jul; OMAP4 validation will start once CORE DVFS with min defconfig is functional on OMAP4 07-Jul: Requires DVFS functionality which is available on OMAP3 today and will be done for OMAP4 by the target date
Extensive testing on OMAP3 & OMAP4 and rework to address review comments Vibhore New: TBD Old: 31-Jul Not started 21-Jul: Needs to be done during PM camp as drivers expressing constraints need to be in place; may happen by Sep end 23-Jun: None None
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