From 9799aca2032ad53418ff4bc0d1a6f2cb4f79b6c0 Mon Sep 17 00:00:00 2001 From: Kevin Hilman Date: Tue, 26 Jan 2010 20:13:02 -0700 Subject: [PATCH 1/1] 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 Signed-off-by: Paul Walmsley --- arch/arm/plat-omap/include/plat/omap_device.h | 4 ++ arch/arm/plat-omap/omap_device.c | 41 +++++++++++++++---- 2 files changed, 37 insertions(+), 8 deletions(-) diff --git a/arch/arm/plat-omap/include/plat/omap_device.h b/arch/arm/plat-omap/include/plat/omap_device.h index dc1fac1d805c..76d49171fed9 100644 --- a/arch/arm/plat-omap/include/plat/omap_device.h +++ b/arch/arm/plat-omap/include/plat/omap_device.h @@ -131,11 +131,15 @@ int omap_device_enable_clocks(struct omap_device *od); */ struct omap_device_pm_latency { u32 deactivate_lat; + u32 deactivate_lat_worst; int (*deactivate_func)(struct omap_device *od); u32 activate_lat; + u32 activate_lat_worst; int (*activate_func)(struct omap_device *od); + u32 flags; }; +#define OMAP_DEVICE_LATENCY_AUTO_ADJUST BIT(1) /* Get omap_device pointer from platform_device pointer */ #define to_omap_device(x) container_of((x), struct omap_device, pdev) 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; -- 2.39.2