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device: Add simple temperature model for devices

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This temperature model has three states:
 * COLD
 * WARM
 * HOT

Device drivers can define the time it requires for the device to get HOT
and COLD. The underlying model assumes an exponential warming and
cooling process and enforces a cool-off time after the device has
reached the HOT state. This cool down period is however shorter than the
specified time in the driver.
This commit is contained in:
Benjamin Berg
2021-04-21 17:16:03 +02:00
parent 96e5888110
commit a2d950044d
8 changed files with 243 additions and 0 deletions
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114
libfprint/fpi-device.c
View File

@@ -19,6 +19,8 @@
*/
#define FP_COMPONENT "device"
#include <math.h>
#include "fpi-log.h"
#include "fp-device-private.h"
@@ -851,6 +853,8 @@ fp_device_task_return_in_idle_cb (gpointer user_data)
priv->current_action = FPI_DEVICE_ACTION_NONE;
priv->current_task_idle_return_source = NULL;
fpi_device_update_temp (data->device, FALSE);
if (action == FPI_DEVICE_ACTION_OPEN &&
data->type != FP_DEVICE_TASK_RETURN_ERROR)
{
@@ -1685,3 +1689,113 @@ fpi_device_report_finger_status_changes (FpDevice *device,
return fpi_device_report_finger_status (device, finger_status);
}
static void
update_temp_timeout (FpDevice *device, gpointer user_data)
{
FpDevicePrivate *priv = fp_device_get_instance_private (device);
fpi_device_update_temp (device, priv->temp_last_active);
}
/**
* fpi_device_update_temp:
* @device: The #FpDevice
* @is_active: Whether the device is now active
*
* Purely internal function to update the temperature. Also ensure that the
* state is updated once a threshold is reached.
*/
void
fpi_device_update_temp (FpDevice *device, gboolean is_active)
{
FpDevicePrivate *priv = fp_device_get_instance_private (device);
gint64 now = g_get_monotonic_time ();
gdouble passed_seconds;
gdouble alpha;
gdouble next_threshold;
gdouble old_ratio;
FpTemperature old_temp;
g_autofree char *old_temp_str = NULL;
g_autofree char *new_temp_str = NULL;
if (priv->temp_hot_seconds < 0)
{
g_debug ("Not updating temperature model, device can run continuously!");
return;
}
passed_seconds = (now - priv->temp_last_update) / 1e6;
old_ratio = priv->temp_current_ratio;
if (priv->temp_last_active)
{
alpha = exp (-passed_seconds / priv->temp_hot_seconds);
priv->temp_current_ratio = alpha * priv->temp_current_ratio + 1 - alpha;
}
else
{
alpha = exp (-passed_seconds / priv->temp_cold_seconds);
priv->temp_current_ratio = alpha * priv->temp_current_ratio;
}
priv->temp_last_active = is_active;
priv->temp_last_update = now;
old_temp = priv->temp_current;
if (priv->temp_current_ratio < TEMP_COLD_THRESH)
{
priv->temp_current = FP_TEMPERATURE_COLD;
next_threshold = is_active ? TEMP_COLD_THRESH : -1.0;
}
else if (priv->temp_current_ratio < TEMP_HOT_WARM_THRESH)
{
priv->temp_current = FP_TEMPERATURE_WARM;
next_threshold = is_active ? TEMP_WARM_HOT_THRESH : TEMP_COLD_THRESH;
}
else if (priv->temp_current_ratio < TEMP_WARM_HOT_THRESH)
{
/* Keep HOT until we reach TEMP_HOT_WARM_THRESH */
if (priv->temp_current != FP_TEMPERATURE_HOT)
priv->temp_current = FP_TEMPERATURE_WARM;
next_threshold = is_active ? TEMP_WARM_HOT_THRESH : TEMP_HOT_WARM_THRESH;
}
else
{
priv->temp_current = FP_TEMPERATURE_HOT;
next_threshold = is_active ? -1.0 : TEMP_HOT_WARM_THRESH;
}
old_temp_str = g_enum_to_string (FP_TYPE_TEMPERATURE, old_temp);
new_temp_str = g_enum_to_string (FP_TYPE_TEMPERATURE, priv->temp_current);
g_debug ("Updated temperature model after %0.2f seconds, ratio %0.2f -> %0.2f, active %d -> %d, %s -> %s",
passed_seconds,
old_ratio,
priv->temp_current_ratio,
priv->temp_last_active,
is_active,
old_temp_str,
new_temp_str);
if (priv->temp_current != old_temp)
g_object_notify (G_OBJECT (device), "temperature");
g_clear_pointer (&priv->temp_timeout, g_source_destroy);
if (next_threshold < 0)
return;
/* Set passed_seconds to the time until the next update is needed */
if (is_active)
passed_seconds = -priv->temp_hot_seconds * log ((next_threshold - 1.0) / (priv->temp_current_ratio - 1.0));
else
passed_seconds = -priv->temp_cold_seconds * log (next_threshold / priv->temp_current_ratio);
passed_seconds += TEMP_DELAY_SECONDS;
priv->temp_timeout = fpi_device_add_timeout (device,
passed_seconds * 1000,
update_temp_timeout,
NULL, NULL);
}