SRF Replacement - Constraints Part

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Contents

Introduction

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);
	else
		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_OSWR] = 30,
  [FUNC_PWRST_CSWR] = 5,
  [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: 24-Aug Old: 13-Aug, 06-Aug 30-Jul, 22-Jul In progress Posted OMAP3 patches to LO; OMAP4 testing is ongoing - target 24-Aug for posting11-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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