linux-kernel - [PATCH v2] cpuidle/powernv: Populate cpuidle state details by querying the device-tree

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Date:	Wed,  1 Oct 2014 13:15:02 +0530
From:	"Shreyas B. Prabhu" <shreyas@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
	linux-pm@...r.kernel.org, "Rafael J. Wysocki" <rjw@...ysocki.net>,
	Rob Herring <robh+dt@...nel.org>,
	Grant Likely <grant.likely@...aro.org>,
	devicetree@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	Michael Ellerman <mpe@...erman.id.au>,
	"Shreyas B. Prabhu" <shreyas@...ux.vnet.ibm.com>
Subject: [PATCH v2] cpuidle/powernv: Populate cpuidle state details by querying the device-tree

From: Preeti U Murthy <preeti@...ux.vnet.ibm.com>

We hard code the metrics relevant for cpuidle states in the kernel today.
Instead pick them up from the device tree so that they remain relevant
and updated for the system that the kernel is running on.

Cc: linux-pm@...r.kernel.org
Cc: Rafael J. Wysocki <rjw@...ysocki.net>
Cc: Rob Herring <robh+dt@...nel.org>
Cc: Grant Likely <grant.likely@...aro.org>
Cc: devicetree@...r.kernel.org
Cc: linuxppc-dev@...ts.ozlabs.org
Cc: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Preeti U. Murthy <preeti@...ux.vnet.ibm.com>
Signed-off-by: Shreyas B. Prabhu <shreyas@...ux.vnet.ibm.com>
---
v2:
Rebased on 3.17-rc7
Separated from 'powerpc/powernv: Support for fastsleep and winkle'

v1:
Initial post
https://lkml.org/lkml/2014/8/25/456

diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
index a64be57..2426a4b 100644
--- a/drivers/cpuidle/cpuidle-powernv.c
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -163,7 +163,8 @@ static int powernv_add_idle_states(void)
 	int nr_idle_states = 1; /* Snooze */
 	int dt_idle_states;
 	const __be32 *idle_state_flags;
-	u32 len_flags, flags;
+	const __be32 *idle_state_latency;
+	u32 len_flags, flags, latency_ns;
 	int i;
 
 	/* Currently we have snooze statically defined */
@@ -180,18 +181,32 @@ static int powernv_add_idle_states(void)
 		return nr_idle_states;
 	}
 
+	idle_state_latency = of_get_property(power_mgt,
+			"ibm,cpu-idle-state-latencies-ns", NULL);
+	if (!idle_state_latency) {
+		pr_warn("DT-PowerMgmt: missing ibm,cpu-idle-state-latencies-ns\n");
+		return nr_idle_states;
+	}
+
 	dt_idle_states = len_flags / sizeof(u32);
 
 	for (i = 0; i < dt_idle_states; i++) {
 
 		flags = be32_to_cpu(idle_state_flags[i]);
+
+		/* Cpuidle accepts exit_latency in us and we estimate best case
+		 * target residency to be 10x exit_latency
+		 */
+		latency_ns = be32_to_cpu(idle_state_latency[i]);
 		if (flags & IDLE_USE_INST_NAP) {
 			/* Add NAP state */
 			strcpy(powernv_states[nr_idle_states].name, "Nap");
 			strcpy(powernv_states[nr_idle_states].desc, "Nap");
 			powernv_states[nr_idle_states].flags = CPUIDLE_FLAG_TIME_VALID;
-			powernv_states[nr_idle_states].exit_latency = 10;
-			powernv_states[nr_idle_states].target_residency = 100;
+			powernv_states[nr_idle_states].exit_latency =
+					((unsigned int)latency_ns) / 1000;
+			powernv_states[nr_idle_states].target_residency =
+					((unsigned int)latency_ns / 100);
 			powernv_states[nr_idle_states].enter = &nap_loop;
 			nr_idle_states++;
 		}
@@ -202,8 +217,10 @@ static int powernv_add_idle_states(void)
 			strcpy(powernv_states[nr_idle_states].desc, "FastSleep");
 			powernv_states[nr_idle_states].flags =
 				CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TIMER_STOP;
-			powernv_states[nr_idle_states].exit_latency = 300;
-			powernv_states[nr_idle_states].target_residency = 1000000;
+			powernv_states[nr_idle_states].exit_latency =
+					((unsigned int)latency_ns) / 1000;
+			powernv_states[nr_idle_states].target_residency =
+					((unsigned int)latency_ns / 100);
 			powernv_states[nr_idle_states].enter = &fastsleep_loop;
 			nr_idle_states++;
 		}

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/