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  1. 01 11月, 2011 1 次提交
  3. 15 9月, 2011 2 次提交
  5. 27 8月, 2011 2 次提交
    • T
      rtc: twl: Fix registration vs. init order · 7e72c686
      由 Todd Poynor 提交于 
      Only register as an RTC device after the hardware has been
successfully initialized.  The RTC class driver will call
back to this driver to read a pending alarm, and other
drivers watching for new devices on the RTC class may
read the RTC time upon registration.  Such access might
occur while the RTC is stopped, prior to clearing
pending alarms, etc.

The new ordering also avoids leaving the platform
device drvdata set to an unregistered struct rtc_device *
on probe errors.
Signed-off-by: NTodd Poynor <toddpoynor@google.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
      7e72c686
    • M
      rtc: Initialized rtc_time->tm_isdst · a7402deb
      由 Mike Waychison 提交于 
      Even though the Linux kernel does not use the tm_isdst field, it is
exposed as part of the ABI.  This field can accidentally be left
initialized, which is why we currently memset buffers returned to
userland in rtc_read_time.

There is a case however where the field can return garbage from the
stack though when using the RTC_ALM_READ ioctl on the rtc device.  This
ioctl invokes rtc_read_alarm, which is careful to memset the rtc_wkalrm
buffer that is copied to userland, but it then uses a struct copy to
assign to alarm->time given the return value from rtc_ktime_to_tm().

rtc_ktime_to_tm() is implemented by calling rtc_time_to_tm using a
derivative seconds counds from ktime, but rtc_time_to_tm does not assign
a value to ->tm_isdst.  This results in garbage from rtc_ktime_to_tm()'s
frame ending up being copied out to userland as part of the returned
rtc_wkalrm.

Fix this by initializing rtc_time->tm_isdst to 0 in rtc_time_to_tm.
Signed-off-by: NMike Waychison <mikew@google.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
      a7402deb
  7. 26 8月, 2011 2 次提交
  9. 11 8月, 2011 4 次提交
  11. 04 8月, 2011 1 次提交
  13. 27 7月, 2011 6 次提交
  15. 26 7月, 2011 5 次提交
  17. 02 7月, 2011 6 次提交
  19. 28 6月, 2011 1 次提交
  21. 24 6月, 2011 1 次提交
  23. 22 6月, 2011 1 次提交
    • J
      rtc: Avoid accumulating time drift in suspend/resume · 3dcad5ff
      由 John Stultz 提交于 
      Because the RTC interface is only a second granular interface,
each time we read from the RTC for suspend/resume, we introduce a
half second (on average) of error.

In order to avoid this error accumulating as the system is suspended
over and over, this patch measures the time delta between the RTC
and the system CLOCK_REALTIME.

If the delta is less then 2 seconds from the last suspend, we compensate
by using the previous time delta (keeping it close). If it is larger
then 2 seconds, we assume the clock was set or has been changed, so we
do no correction and update the delta.

Note: If NTP is running, ths could seem to "fight" with the NTP corrected
time, where as if the system time was off by 1 second, and NTP slewed the
value in, a suspend/resume cycle could undo this correction, by trying to
restore the previous offset from the RTC. However, without this patch,
since each read could cause almost a full second worth of error, its
possible to get almost 2 seconds of error just from the suspend/resume
cycle alone, so this about equal to any offset added by the compensation.

Further on systems that suspend/resume frequently, this should keep time
closer then NTP could compensate for if the errors were allowed to
accumulate.

Credits to Arve Hjønnevåg for suggesting this solution.

This patch also improves some of the variable names and adds more clear
comments.

CC: Arve Hjønnevåg <arve@android.com>
CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
      3dcad5ff
  25. 10 6月, 2011 1 次提交
  27. 09 6月, 2011 2 次提交
  29. 02 6月, 2011 2 次提交
  31. 27 5月, 2011 3 次提交