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authorKevin Hilman <khilman@deeprootsystems.com>2010-01-26 20:13:02 -0700
committerPaul Walmsley <paul@pwsan.com>2010-01-26 20:13:02 -0700
commit9799aca2032ad53418ff4bc0d1a6f2cb4f79b6c0 (patch)
treef8cd85a140eb5d1bf77fff3dbec78ae93f6be183 /arch/arm/plat-omap/omap_device.c
parentf0271d65f9ac511d2e3e1fdbcd7418a5a7df0769 (diff)
OMAP: omap_device: optionally auto-adjust device activate/deactivate latencies
First, this patch adds new worst-case latency values to the omap_device_pm_latency struct. Here the worst-case measured latencies for the activate and deactivate hooks are stored. In addition, add an option to auto-adjust the latency values used for device activate/deactivate. By setting a new 'OMAP_DEVICE_LATENCY_AUTO_ADJUST' flag in the omap_device_pm_latency struct, the omap_device layer automatically adjusts the activate/deactivate latencies to the worst-case measured values. Anytime a new worst-case value is found, it is printed to the console. Here is an example log during boot using UART2 s an example. After boot, the OPP is manually changed to the 125MHz OPP: [...] Freeing init memory: 128K omap_device: serial8250.2: new worst case deactivate latency 0: 30517 omap_device: serial8250.2: new worst case activate latency 0: 30517 omap_device: serial8250.2: new worst case activate latency 0: 218139648 omap_device: serial8250.2: new worst case deactivate latency 0: 61035 omap_device: serial8250.2: new worst case activate latency 0: 278076171 omap_device: serial8250.2: new worst case activate latency 0: 298614501 omap_device: serial8250.2: new worst case activate latency 0: 327331542 / # echo 125000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed omap_device: serial8250.2: new worst case deactivate latency 0: 91552 Motivation: this can be used as a technique to automatically determine the worst case latency values. The current method of printing a warning on every violation is too noisy to actually interact the console in order to set low OPP to discover latencies. Another motivation for this patch is that the activate/deactivate latenices can vary depending on the idlemode of the device. While working on the UARTs, I noticed that when using no-idle, the activate latencies were as high as several hundred msecs as shown above. When the UARTs are in smart-idle, the max latency is well under 100 usecs. Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com> Signed-off-by: Paul Walmsley <paul@pwsan.com>
Diffstat (limited to 'arch/arm/plat-omap/omap_device.c')
-rw-r--r--arch/arm/plat-omap/omap_device.c41
1 files changed, 33 insertions, 8 deletions
diff --git a/arch/arm/plat-omap/omap_device.c b/arch/arm/plat-omap/omap_device.c
index 1e5648d3e3d8..d8c75c8f78d7 100644
--- a/arch/arm/plat-omap/omap_device.c
+++ b/arch/arm/plat-omap/omap_device.c
@@ -148,10 +148,22 @@ static int _omap_device_activate(struct omap_device *od, u8 ignore_lat)
"%llu nsec\n", od->pdev.name, od->pm_lat_level,
act_lat);
- WARN(act_lat > odpl->activate_lat, "omap_device: %s.%d: "
- "activate step %d took longer than expected (%llu > %d)\n",
- od->pdev.name, od->pdev.id, od->pm_lat_level,
- act_lat, odpl->activate_lat);
+ if (act_lat > odpl->activate_lat) {
+ odpl->activate_lat_worst = act_lat;
+ if (odpl->flags & OMAP_DEVICE_LATENCY_AUTO_ADJUST) {
+ odpl->activate_lat = act_lat;
+ pr_warning("omap_device: %s.%d: new worst case "
+ "activate latency %d: %llu\n",
+ od->pdev.name, od->pdev.id,
+ od->pm_lat_level, act_lat);
+ } else
+ pr_warning("omap_device: %s.%d: activate "
+ "latency %d higher than exptected. "
+ "(%llu > %d)\n",
+ od->pdev.name, od->pdev.id,
+ od->pm_lat_level, act_lat,
+ odpl->activate_lat);
+ }
od->dev_wakeup_lat -= odpl->activate_lat;
}
@@ -204,10 +216,23 @@ static int _omap_device_deactivate(struct omap_device *od, u8 ignore_lat)
"%llu nsec\n", od->pdev.name, od->pm_lat_level,
deact_lat);
- WARN(deact_lat > odpl->deactivate_lat, "omap_device: %s.%d: "
- "deactivate step %d took longer than expected "
- "(%llu > %d)\n", od->pdev.name, od->pdev.id,
- od->pm_lat_level, deact_lat, odpl->deactivate_lat);
+ if (deact_lat > odpl->deactivate_lat) {
+ odpl->deactivate_lat_worst = deact_lat;
+ if (odpl->flags & OMAP_DEVICE_LATENCY_AUTO_ADJUST) {
+ odpl->deactivate_lat = deact_lat;
+ pr_warning("omap_device: %s.%d: new worst case "
+ "deactivate latency %d: %llu\n",
+ od->pdev.name, od->pdev.id,
+ od->pm_lat_level, deact_lat);
+ } else
+ pr_warning("omap_device: %s.%d: deactivate "
+ "latency %d higher than exptected. "
+ "(%llu > %d)\n",
+ od->pdev.name, od->pdev.id,
+ od->pm_lat_level, deact_lat,
+ odpl->deactivate_lat);
+ }
+
od->dev_wakeup_lat += odpl->activate_lat;