Thomas Gleixner 69eca258c8 ntp: Make the RTC sync offset less obscure ... The current RTC set_offset_nsec value is not really intuitive to understand. tsched twrite(t2.tv_sec - 1) t2 (seconds increment) The offset is calculated from twrite based on the assumption that t2 - twrite == 1s. That means for the MC146818 RTC the offset needs to be negative so that the write happens 500ms before t2. It's easier to understand when the whole calculation is based on t2. That avoids negative offsets and the meaning is obvious: t2 - twrite: The time defined by the chip when seconds increment after the write. twrite - tsched: The time for the transport to the point where the chip is updated. ==> set_offset_nsec = t2 - tsched ttransport = twrite - tsched tRTCinc = t2 - twrite ==> set_offset_nsec = ttransport + tRTCinc tRTCinc is a chip property and can be obtained from the data sheet. ttransport depends on how the RTC is connected. It is close to 0 for directly accessible RTCs. For RTCs behind a slow bus, e.g. i2c, it's the time required to send the update over the bus. This can be estimated or even calibrated, but that's a different problem. Adjust the implementation and update comments accordingly. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Link: https://lore.kernel.org/r/20201206220542.263204937@linutronix.de		2020-12-11 10:40:53 +01:00
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Kconfig	rtc: rv3032: Add a driver for Microcrystal RV-3032	2020-10-19 22:47:56 +02:00
Makefile	ntp, rtc: Move rtc_set_ntp_time() to ntp code	2020-12-11 10:40:52 +01:00
class.c	ntp: Make the RTC sync offset less obscure	2020-12-11 10:40:53 +01:00
dev.c	…
interface.c	…
lib.c	…
nvmem.c	…
proc.c	…
rtc-88pm80x.c	…
rtc-88pm860x.c	rtc: 88pm860x: remove useless range check	2020-04-18 22:42:06 +02:00
rtc-ab-b5ze-s3.c	rtc: Replace HTTP links with HTTPS ones	2020-07-16 11:17:52 +02:00
rtc-ab-eoz9.c	…
rtc-ab3100.c	…
rtc-ab8500.c	…
rtc-abx80x.c	rtc: abx80x: Provide debug feedback for invalid dt properties	2020-06-06 00:16:24 +02:00
rtc-ac100.c	…
rtc-armada38x.c	…
rtc-as3722.c	…
rtc-asm9260.c	…
rtc-aspeed.c	…
rtc-at91rm9200.c	…
rtc-at91sam9.c	…
rtc-au1xxx.c	…
rtc-bd70528.c	rtc: bd70528: Avoid double error messaging when IRQ absent	2020-03-23 09:27:17 +01:00
rtc-bq32k.c	rtc: Replace HTTP links with HTTPS ones	2020-07-16 11:17:52 +02:00
rtc-bq4802.c	…
rtc-brcmstb-waketimer.c	…
rtc-cadence.c	…
rtc-cmos.c	ntp: Make the RTC sync offset less obscure	2020-12-11 10:40:53 +01:00
rtc-coh901331.c	…
rtc-core.h	…
rtc-cpcap.c	rtc: cpcap: fix range	2020-07-02 22:32:00 +02:00
rtc-cros-ec.c	…
rtc-da9052.c	rtc: da9052: switch to rtc_time64_to_tm/rtc_tm_to_time64	2020-04-01 12:33:43 +02:00
rtc-da9055.c	…
rtc-da9063.c	…
rtc-davinci.c	…
rtc-digicolor.c	…
rtc-dm355evm.c	…
rtc-ds1216.c	…
rtc-ds1286.c	…
rtc-ds1302.c	…
rtc-ds1305.c	…
rtc-ds1307.c	rtc: ds1307: enable rx8130's backup battery, make it chargeable optionally	2020-09-24 09:56:04 +02:00
rtc-ds1343.c	…
rtc-ds1347.c	…
rtc-ds1374.c	rtc: ds1374: remove unused define	2020-07-21 09:56:46 +02:00
rtc-ds1390.c	…
rtc-ds1511.c	…
rtc-ds1553.c	…
rtc-ds1672.c	…
rtc-ds1685.c	rtc: ds1685: Fix bank switching to avoid endless loop	2020-09-15 11:24:29 +02:00
rtc-ds1742.c	…
rtc-ds2404.c	…
rtc-ds3232.c	…
rtc-efi.c	…
rtc-em3027.c	…
rtc-ep93xx.c	…
rtc-fm3130.c	…
rtc-fsl-ftm-alarm.c	rtc: fsl-ftm-alarm: update acpi device id	2020-08-21 00:20:38 +02:00
rtc-ftrtc010.c	…
rtc-generic.c	…
rtc-goldfish.c	rtc: goldfish: Enable interrupt in set_alarm() when necessary	2020-07-16 11:15:43 +02:00
rtc-hid-sensor-time.c	…
rtc-hym8563.c	…
rtc-imx-sc.c	rtc: imx-sc: Align imx sc msg structs to 4	2020-03-29 22:08:35 +02:00
rtc-imxdi.c	rtc: imxdi: fix trivial typos	2020-07-02 22:32:01 +02:00
rtc-isl1208.c	…
rtc-isl12022.c	…
rtc-isl12026.c	…
rtc-jz4740.c	rtc: ingenic: Reset regulator register in probe	2020-05-11 16:35:05 +02:00
rtc-lp8788.c	…
rtc-lpc24xx.c	rtc: remove unnecessary error message after platform_get_irq	2020-04-15 09:56:17 +02:00
rtc-lpc32xx.c	…
rtc-ls1x.c	…
rtc-m41t80.c	treewide: Use fallthrough pseudo-keyword	2020-08-23 17:36:59 -05:00
rtc-m41t93.c	…
rtc-m41t94.c	…
rtc-m48t35.c	…
rtc-m48t59.c	…
rtc-m48t86.c	…
rtc-max6900.c	…
rtc-max6902.c	…
rtc-max6916.c	…
rtc-max8907.c	…
rtc-max8925.c	…
rtc-max8997.c	…
rtc-max8998.c	…
rtc-max77686.c	rtc: max77686: Fix wake-ups for max77620	2020-08-07 23:29:47 +02:00
rtc-mc13xxx.c	rtc: mc13xxx: fix a double-unlock issue	2020-05-11 16:21:50 +02:00
rtc-mc146818-lib.c	rtc: mc146818: Reduce spinlock section in mc146818_set_time()	2020-12-11 10:40:52 +01:00
rtc-mcp795.c	rtc: Replace HTTP links with HTTPS ones	2020-07-16 11:17:52 +02:00
rtc-meson-vrtc.c	rtc: meson: simplify the return expression of meson_vrtc_probe	2020-09-29 22:19:15 +02:00
rtc-meson.c	…
rtc-moxart.c	…
rtc-mpc5121.c	rtc: mpc5121: Use correct return value for mpc5121_rtc_probe()	2020-05-30 04:12:38 +02:00
rtc-mrst.c	…
rtc-msm6242.c	…
rtc-mt2712.c	rtc: mt2712: switch to devm_platform_ioremap_resource	2020-04-18 22:42:04 +02:00
rtc-mt6397.c	rtc: mt6397: Remove unused member dev	2020-10-15 12:01:29 +02:00
rtc-mt7622.c	…
rtc-mv.c	…
rtc-mxc.c	rtc: mxc: Use devm_add_action_or_reset() for calls to clk_disable_unprepare()	2020-03-22 22:10:41 +01:00
rtc-mxc_v2.c	…
rtc-omap.c	rtc: omap: drop unused dt-bindings header	2020-03-23 09:27:17 +01:00
rtc-opal.c	…
rtc-palmas.c	…
rtc-pcap.c	…
rtc-pcf2123.c	…
rtc-pcf2127.c	rtc: pcf2127: fix a bug when not specify interrupts property	2020-09-15 12:25:44 +02:00
rtc-pcf8523.c	treewide: Use fallthrough pseudo-keyword	2020-08-23 17:36:59 -05:00
rtc-pcf8563.c	…
rtc-pcf8583.c	…
rtc-pcf50633.c	…
rtc-pcf85063.c	treewide: Use fallthrough pseudo-keyword	2020-08-23 17:36:59 -05:00
rtc-pcf85363.c	…
rtc-pic32.c	…
rtc-pl030.c	…
rtc-pl031.c	rtc: pl031: fix set_alarm by adding back call to alarm_irq_enable	2020-07-16 11:27:03 +02:00
rtc-pm8xxx.c	rtc: pm8xxx: clear alarm register when alarm is not enabled	2020-03-23 09:27:17 +01:00
rtc-ps3.c	…
rtc-pxa.c	…
rtc-r7301.c	…
rtc-r9701.c	rtc: r9701: set range	2020-10-19 22:48:55 +02:00
rtc-rc5t583.c	…
rtc-rc5t619.c	rtc: rc5t619: Fix an ERR_PTR vs NULL check	2020-04-15 09:58:24 +02:00
rtc-rk808.c	…
rtc-rp5c01.c	…
rtc-rs5c313.c	rtc: rtc-rs5c313: Convert to module_platform_driver()	2020-08-21 00:13:44 +02:00
rtc-rs5c348.c	…
rtc-rs5c372.c	…
rtc-rtd119x.c	…
rtc-rv3028.c	rtc: rv3028: ensure ram configuration registers are saved	2020-10-15 12:09:35 +02:00
rtc-rv3029c2.c	…
rtc-rv3032.c	rtc: rv3032: Add a driver for Microcrystal RV-3032	2020-10-19 22:47:56 +02:00
rtc-rv8803.c	rtc: rv8803: simplify the return expression of rv8803_nvram_write	2020-09-29 22:20:10 +02:00
rtc-rx4581.c	…
rtc-rx6110.c	…
rtc-rx8010.c	rtc: rx8010: rename rx8010_init_client() to rx8010_init()	2020-09-29 22:18:10 +02:00
rtc-rx8025.c	…
rtc-rx8581.c	…
rtc-s3c.c	rtc: s3c: Simplify with dev_err_probe()	2020-09-15 10:42:36 +02:00
rtc-s3c.h	…
rtc-s5m.c	…
rtc-s35390a.c	…
rtc-sa1100.c	…
rtc-sa1100.h	…
rtc-sc27xx.c	…
rtc-sd3078.c	…
rtc-sh.c	…
rtc-sirfsoc.c	…
rtc-snvs.c	rtc: snvs: Add necessary clock operations for RTC APIs	2020-05-30 03:17:48 +02:00
rtc-spear.c	…
rtc-st-lpc.c	rtc: st-lpc: Constify st_rtc_ops	2020-09-15 11:21:50 +02:00
rtc-starfire.c	…
rtc-stk17ta8.c	…
rtc-stm32.c	…
rtc-stmp3xxx.c	treewide: Use fallthrough pseudo-keyword	2020-08-23 17:36:59 -05:00
rtc-sun4v.c	…
rtc-sun6i.c	rtc: sun6i: let the core handle rtc range	2020-04-02 18:47:29 +02:00
rtc-sunxi.c	…
rtc-tegra.c	…
rtc-test.c	…
rtc-tps6586x.c	…
rtc-tps65910.c	…
rtc-tps80031.c	…
rtc-twl.c	…
rtc-tx4939.c	…
rtc-v3020.c	…
rtc-vr41xx.c	…
rtc-vt8500.c	…
rtc-wilco-ec.c	…
rtc-wm831x.c	…
rtc-wm8350.c	…
rtc-x1205.c	…
rtc-xgene.c	…
rtc-zynqmp.c	…
sysfs.c	…