Recompute the boot to realtime delta at iio ts channel read time

The RTC can be moved backward or forward at any time... err on
the side of safety, even if there are still potential issues with
this implementation (delay between kernel calls, possibility that
we get scheduled out, or that the clock is adjusted after the iio
buffer was stored...).

Change-Id: If1a517e8e2273ef479bd6095975df26d4aa4d2cd
Signed-off-by: Patrick Porlan <patrick.porlan@intel.com>

diff --git a/control.c b/control.c
index 9d8baa4..709b376 100644 (file)
--- a/control.c
+++ b/control.c
@@ -30,8 +30,6 @@ static int poll_fd; /* epoll instance covering all enabled sensors */
 
 static int active_poll_sensors; /* Number of enabled poll-mode sensors */
 
-static int64_t sys_to_rt_delta;        /* delta between system and realtime clocks */
-
 /* We use pthread condition variables to get worker threads out of sleep */
 static pthread_condattr_t thread_cond_attr     [MAX_SENSORS];
 static pthread_cond_t     thread_release_cond  [MAX_SENSORS];
@@ -597,9 +595,6 @@ int sensor_activate(int s, int enabled)
        /* Prepare the report timestamp field for the first event, see set_report_ts method */
        sensor_info[s].report_ts = 0;
 
-       sys_to_rt_delta = get_timestamp_realtime() - get_timestamp_boot();
-
-
        /* If we want to activate gyro calibrated and gyro uncalibrated is activated
         * Deactivate gyro uncalibrated - Uncalibrated releases handler
         * Activate gyro calibrated     - Calibrated has handler
@@ -850,6 +845,7 @@ static int integrate_device_report (int dev_num)
        int size;
        int64_t ts = 0;
        int ts_offset = 0;      /* Offset of iio timestamp, if provided */
+       int64_t sys_to_rt_delta;
 
        /* There's an incoming report on the specified iio device char dev fd */
 
@@ -935,6 +931,8 @@ static int integrate_device_report (int dev_num)
 
        ALOGV("Driver timestamp on iio device %d: ts=%lld\n", dev_num, ts);
 
+       sys_to_rt_delta = get_timestamp_realtime() - get_timestamp_boot();
+
        for (s=0; s<MAX_SENSORS; s++)
                if (sensor_info[s].dev_num == dev_num && sensor_info[s].enabled)
                        set_report_ts(s, ts - sys_to_rt_delta);