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3dcad5ff08
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: John Stultz <john.stultz@linaro.org> |
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| .. | ||
| class.c | ||
| hctosys.c | ||
| interface.c | ||
| Kconfig | ||
| Makefile | ||
| rtc-88pm860x.c | ||
| rtc-ab3100.c | ||
| rtc-ab8500.c | ||
| rtc-at32ap700x.c | ||
| rtc-at91rm9200.c | ||
| rtc-at91sam9.c | ||
| rtc-au1xxx.c | ||
| rtc-bfin.c | ||
| rtc-bq32k.c | ||
| rtc-bq4802.c | ||
| rtc-cmos.c | ||
| rtc-coh901331.c | ||
| rtc-core.h | ||
| rtc-davinci.c | ||
| rtc-dev.c | ||
| rtc-dm355evm.c | ||
| rtc-ds1216.c | ||
| rtc-ds1286.c | ||
| rtc-ds1302.c | ||
| rtc-ds1305.c | ||
| rtc-ds1307.c | ||
| rtc-ds1374.c | ||
| rtc-ds1390.c | ||
| rtc-ds1511.c | ||
| rtc-ds1553.c | ||
| rtc-ds1672.c | ||
| rtc-ds1742.c | ||
| rtc-ds3232.c | ||
| rtc-ds3234.c | ||
| rtc-efi.c | ||
| rtc-em3027.c | ||
| rtc-ep93xx.c | ||
| rtc-fm3130.c | ||
| rtc-generic.c | ||
| rtc-imxdi.c | ||
| rtc-isl1208.c | ||
| rtc-isl12022.c | ||
| rtc-jz4740.c | ||
| rtc-lib.c | ||
| rtc-lpc32xx.c | ||
| rtc-m41t80.c | ||
| rtc-m41t93.c | ||
| rtc-m41t94.c | ||
| rtc-m48t35.c | ||
| rtc-m48t59.c | ||
| rtc-m48t86.c | ||
| rtc-max6900.c | ||
| rtc-max6902.c | ||
| rtc-max8925.c | ||
| rtc-max8998.c | ||
| rtc-mc13xxx.c | ||
| rtc-mpc5121.c | ||
| rtc-mrst.c | ||
| rtc-msm6242.c | ||
| rtc-mv.c | ||
| rtc-mxc.c | ||
| rtc-nuc900.c | ||
| rtc-omap.c | ||
| rtc-pcap.c | ||
| rtc-pcf2123.c | ||
| rtc-pcf8563.c | ||
| rtc-pcf8583.c | ||
| rtc-pcf50633.c | ||
| rtc-pl030.c | ||
| rtc-pl031.c | ||
| rtc-proc.c | ||
| rtc-ps3.c | ||
| rtc-puv3.c | ||
| rtc-pxa.c | ||
| rtc-r9701.c | ||
| rtc-rp5c01.c | ||
| rtc-rs5c313.c | ||
| rtc-rs5c348.c | ||
| rtc-rs5c372.c | ||
| rtc-rv3029c2.c | ||
| rtc-rx8025.c | ||
| rtc-rx8581.c | ||
| rtc-s3c.c | ||
| rtc-s35390a.c | ||
| rtc-sa1100.c | ||
| rtc-sh.c | ||
| rtc-spear.c | ||
| rtc-starfire.c | ||
| rtc-stk17ta8.c | ||
| rtc-stmp3xxx.c | ||
| rtc-sun4v.c | ||
| rtc-sysfs.c | ||
| rtc-tegra.c | ||
| rtc-test.c | ||
| rtc-tile.c | ||
| rtc-twl.c | ||
| rtc-tx4939.c | ||
| rtc-v3020.c | ||
| rtc-vr41xx.c | ||
| rtc-vt8500.c | ||
| rtc-wm831x.c | ||
| rtc-wm8350.c | ||
| rtc-x1205.c | ||