linux/drivers/rtc
Rasmus Villemoes 4d6af37caf rtc: isl12022: remove wrong warning for low battery level
There are multiple problems with this warning.

First of all, it triggers way too often, in fact nearly on every boot,
because the SR_LBAT85/SR_LBAT75 bits have another meaning when in
battery backup mode. Quoting from the data sheet:

  LOW BATTERY INDICATOR 85% BIT (LBAT85)

  In Normal Mode (VDD), this bit indicates when the battery level has
  dropped below the pre-selected trip levels. [...] The LBAT85
  detection happens automatically once every minute when seconds
  register reaches 59.

  In Battery Mode (VBAT), this bit indicates the device has entered
  into battery mode by polling once every 10 minutes. The LBAT85
  detection happens automatically once when the minute register
  reaches x9h or x0h minutes.

Similar wording applies to the LBAT75 bit.

This means that if the device is powered off for more than 10 minutes,
the LBAT85 bit is guaranteed to be set. Upon power-on, unless we're
close enough to the end of a minute and/or the boot is slow enough
that the second register passes 59, the LBAT85 bit is still set when
the kernel (or early userspace) reads the RTC to set the system's
wallclock time.

Another minor problem is with the bit logic. If the 75% level is
reached, logically we're also below 85%, so both bits would most
likely be set. So even if the battery is below 75%, the warning would
still say "voltage dropped below 85%".

A third problem is that the driver and current DT binding offer no way
to indicate the nominal battery level and/or settings of the Battery
Level Monitor Trip Bits. Since the default value of the VB85TP[2:0] and
VB75TP[2:0] bits are 000, this means the actual setting of the
LBAT85/LBAT75 bits in VDD mode doesn't happen until the battery is below
2.125V/1.875V, which for a standard 3V battery is way too late.

A fourth problem is emitting this warning from ->read_time:
util-linux' hwclock will, in the absence of support for getting an
interrupt when the seconds counter is updated, issue
ioctl(RTC_RD_TIME) in a busy-loop until it sees a change in the
seconds field. In that case, if the battery low bits are set (either
genuinely, more than a minute after boot, due to the battery actually
being low, or as above, bogusly shortly after boot), the kernel log is
swamped with hundreds of identical warnings.

Subsequent patches will add such bindings and driver support, and also
proper support for RTC_VL_READ. For now, remove the broken warning.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Link: https://lore.kernel.org/r/20230615105826.411953-2-linux@rasmusvillemoes.dk
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2023-08-16 01:27:01 +02:00
..
class.c driver core: class: remove module * from class_create() 2023-03-17 15:16:33 +01:00
dev.c rtc: Remove unused rtc_dev_exit(). 2022-06-24 21:24:02 +02:00
interface.c rtc: allow rtc_read_alarm without read_alarm callback 2023-02-22 12:32:05 +01:00
Kconfig rtc: bq4802: add sparc dependency 2023-07-27 23:09:55 +02:00
lib_test.c rtc: lib_test: add MODULE_LICENSE 2021-08-10 23:21:46 +02:00
lib.c rtc: Improve performance of rtc_time64_to_tm(). Add tests. 2021-08-10 00:09:21 +02:00
Makefile rtc: Add rtc driver for the Loongson family chips 2023-06-26 01:19:11 +02:00
nvmem.c rtc: nvmem: emit an error message when nvmem registration fails 2020-11-19 12:50:12 +01:00
proc.c rtc: fix snprintf() checking in is_rtc_hctosys() 2021-05-25 00:36:11 +02:00
rtc-88pm80x.c rtc: 88pm80x: Convert to platform remove callback returning void 2023-03-17 23:03:16 +01:00
rtc-88pm860x.c rtc: 88pm860x: Convert to platform remove callback returning void 2023-03-17 23:03:16 +01:00
rtc-ab8500.c rtc: ab8500: Convert to platform remove callback returning void 2023-03-17 23:03:16 +01:00
rtc-ab-b5ze-s3.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-ab-eoz9.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-abx80x.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-ac100.c rtc: ac100: Convert to platform remove callback returning void 2023-03-17 23:03:17 +01:00
rtc-armada38x.c rtc: remove redundant of_match_ptr() 2023-08-10 09:45:41 +02:00
rtc-as3722.c
rtc-asm9260.c rtc: asm9260: Convert to platform remove callback returning void 2023-03-17 23:03:17 +01:00
rtc-aspeed.c rtc: remove redundant of_match_ptr() 2023-08-10 09:45:41 +02:00
rtc-at91rm9200.c rtc: remove redundant of_match_ptr() 2023-08-10 09:45:41 +02:00
rtc-at91sam9.c rtc: remove redundant of_match_ptr() 2023-08-10 09:45:41 +02:00
rtc-au1xxx.c rtc: au1xxx: convert to SPDX identifier 2021-07-10 01:53:39 +02:00
rtc-bd70528.c rtc: bd70528: Drop BD70528 support 2021-06-20 22:24:52 +02:00
rtc-bq32k.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-bq4802.c
rtc-brcmstb-waketimer.c rtc: brcmstb-waketimer: Convert to platform remove callback returning void 2023-03-17 23:03:17 +01:00
rtc-cadence.c rtc: cadence: Convert to platform remove callback returning void 2023-03-17 23:03:17 +01:00
rtc-cmos.c rtc: cmos: Convert to platform remove callback returning void 2023-03-17 23:03:17 +01:00
rtc-core.h rtc: Remove unused rtc_dev_exit(). 2022-06-24 21:24:02 +02:00
rtc-cpcap.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-cros-ec.c rtc: cros-ec: Convert to platform remove callback returning void 2023-03-17 23:03:17 +01:00
rtc-da9052.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-da9055.c
rtc-da9063.c rtc: da9063: add as wakeup source 2021-12-02 23:23:38 +01:00
rtc-digicolor.c rtc: digicolor: quiet maybe-unused variable warning 2021-02-06 00:58:24 +01:00
rtc-ds1216.c
rtc-ds1286.c
rtc-ds1302.c rtc: ds1302: remove unnecessary spi_set_drvdata() 2022-11-15 21:01:51 +01:00
rtc-ds1305.c spi: make remove callback a void function 2022-02-09 13:00:45 +00:00
rtc-ds1307.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-ds1343.c spi: make remove callback a void function 2022-02-09 13:00:45 +00:00
rtc-ds1347.c rtc: ds1347: fix value written to century register 2022-11-15 21:01:51 +01:00
rtc-ds1374.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-ds1390.c rtc: ds1390: mark OF related data as maybe unused 2023-03-17 23:23:22 +01:00
rtc-ds1511.c rtc: ds1511: remove unused function 2021-04-17 11:21:04 +02:00
rtc-ds1553.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-ds1672.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-ds1685.c rtc: ds1685: Convert to platform remove callback returning void 2023-03-17 23:03:17 +01:00
rtc-ds1742.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-ds2404.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-ds3232.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-efi.c rtc: efi: Avoid spamming the log on RTC read failure 2023-02-22 21:07:53 +01:00
rtc-em3027.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-ep93xx.c rtc: ep93xx: Fix NULL pointer dereference in ep93xx_rtc_read_time 2020-12-03 23:49:31 +01:00
rtc-fm3130.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-fsl-ftm-alarm.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-ftrtc010.c rtc: ftrtc010: Convert to platform remove callback returning void 2023-03-17 23:03:17 +01:00
rtc-gamecube.c rtc: gamecube: Always reset HW_SRNPROT after read 2022-08-23 22:27:58 +02:00
rtc-generic.c
rtc-goldfish.c clocksource/drivers: Add a goldfish-timer clocksource 2022-04-11 11:48:01 +02:00
rtc-hid-sensor-time.c rtc: hid-sensor-time: Convert to platform remove callback returning void 2023-03-17 23:03:17 +01:00
rtc-hym8563.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-imx-sc.c rtc: imx-sc: remove .read_alarm 2021-04-29 23:03:26 +02:00
rtc-imxdi.c rtc: imxdi: add wakeup support 2021-05-25 00:41:25 +02:00
rtc-isl1208.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-isl12022.c rtc: isl12022: remove wrong warning for low battery level 2023-08-16 01:27:01 +02:00
rtc-isl12026.c rtc: isl12026: Drop "_new" from probe callback name 2023-07-27 23:32:08 +02:00
rtc-jz4740.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-loongson.c rtc: Add rtc driver for the Loongson family chips 2023-06-26 01:19:11 +02:00
rtc-lp8788.c
rtc-lpc24xx.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-lpc32xx.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-m41t80.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-m41t93.c
rtc-m41t94.c
rtc-m48t35.c rtc: m48t35: remove SGI-IP27 kludge 2020-03-16 11:12:11 +01:00
rtc-m48t59.c rtc: m48t59: use platform_get_irq_optional 2021-03-11 09:48:09 +01:00
rtc-m48t86.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-max6900.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-max6902.c
rtc-max6916.c
rtc-max8907.c rtc: max8907: Drop unused i2c include 2023-02-01 09:13:35 +01:00
rtc-max8925.c
rtc-max8997.c
rtc-max8998.c
rtc-max77686.c rtc: max77686: Convert to platform remove callback returning void 2023-03-17 23:03:17 +01:00
rtc-mc13xxx.c rtc: mc13xxx: Convert to platform remove callback returning void 2023-03-17 23:03:17 +01:00
rtc-mc146818-lib.c rtc: mc146818-lib: reduce RTC_UIP polling period 2022-06-24 21:23:50 +02:00
rtc-mcp795.c rtc: mcp795: Add SPI ID table 2021-10-01 23:28:28 +02:00
rtc-meson-vrtc.c rtc: meson-vrtc: Use ktime_get_real_ts64() to get the current time 2023-03-21 21:15:10 +01:00
rtc-meson.c rtc: meson: Fix email address in MODULE_AUTHOR 2022-05-18 00:20:39 +02:00
rtc-moxart.c rtc: moxart: switch to using gpiod API 2023-02-09 23:31:46 +01:00
rtc-mpc5121.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-mpfs.c rtc: mpfs: Convert to platform remove callback returning void 2023-03-17 23:03:17 +01:00
rtc-msc313.c rtc: msc313: Fix function prototype mismatch in msc313_rtc_probe() 2022-12-11 18:14:01 +01:00
rtc-msm6242.c
rtc-mt2712.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-mt6397.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-mt7622.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-mv.c rtc: mv: remove mv_rtc_alarm_ops 2021-01-16 23:19:26 +01:00
rtc-mxc_v2.c rtc: mxc_v2: Convert to platform remove callback returning void 2023-03-17 23:03:17 +01:00
rtc-mxc.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-nct3018y.c rtc: remove redundant of_match_ptr() 2023-08-10 09:45:41 +02:00
rtc-ntxec.c rtc: New driver for RTC in Netronix embedded controller 2021-03-10 11:06:33 +00:00
rtc-nxp-bbnsm.c rtc: bbnsm: Add the bbnsm rtc support 2023-02-22 12:25:32 +01:00
rtc-omap.c rtc: omap: include header for omap_rtc_power_off_program prototype 2023-03-17 23:22:45 +01:00
rtc-opal.c rtc: opal: switch to RTC_FEATURE_UPDATE_INTERRUPT 2022-03-23 19:58:39 +01:00
rtc-optee.c rtc: optee: add RTC driver for OP-TEE RTC PTA 2022-03-25 11:42:50 +01:00
rtc-palmas.c rtc: palmas: Convert to platform remove callback returning void 2023-03-17 23:03:17 +01:00
rtc-pcap.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-pcf2123.c rtc: pcf2123: use IRQ flags obtained from fwnode 2023-02-01 09:13:35 +01:00
rtc-pcf2127.c rtc: pcf2127: add UIE support for PCF2131 2023-07-27 22:54:53 +02:00
rtc-pcf8523.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-pcf8563.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-pcf8583.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-pcf50633.c rtc: pcf50633: Convert to platform remove callback returning void 2023-03-17 23:03:18 +01:00
rtc-pcf85063.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-pcf85363.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-pic32.c rtc: pic32: Convert to platform remove callback returning void 2023-03-17 23:03:18 +01:00
rtc-pl030.c amba: Make the remove callback return void 2021-02-02 14:25:50 +01:00
rtc-pl031.c rtc: pl031: fix rtc features null pointer dereference 2022-03-23 19:58:37 +01:00
rtc-pm8xxx.c rtc: pm8xxx: Convert to platform remove callback returning void 2023-03-17 23:03:18 +01:00
rtc-ps3.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-pxa.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-r7301.c rtc: r7301: Replace spin_lock_irqsave with spin_lock in hard IRQ 2021-02-06 00:50:47 +01:00
rtc-r9701.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-rc5t583.c rtc: rc5t583: Convert to platform remove callback returning void 2023-03-17 23:03:18 +01:00
rtc-rc5t619.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-rk808.c rtc: rk808: reduce 'struct rk808' usage 2022-12-11 20:56:33 +01:00
rtc-rp5c01.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-rs5c313.c rtc: rs5c313: correct some spelling mistakes 2022-12-15 23:34:31 +01:00
rtc-rs5c348.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-rs5c372.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-rtd119x.c rtc: rtd119x: Convert to platform remove callback returning void 2023-03-17 23:03:18 +01:00
rtc-rv3028.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-rv3029c2.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-rv3032.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-rv8803.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-rx4581.c
rtc-rx6110.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-rx8010.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-rx8025.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-rx8581.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-rzn1.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-s3c.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-s3c.h
rtc-s5m.c rtc: s5m: Drop S5M8763 support 2023-04-26 11:40:26 +01:00
rtc-s35390a.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-sa1100.c rtc: sa1100: Convert to platform remove callback returning void 2023-03-17 23:03:18 +01:00
rtc-sa1100.h
rtc-sc27xx.c rtc: sc27xx: Fix format of SPDX identifier 2021-07-10 01:53:39 +02:00
rtc-sd3078.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-sh.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-snvs.c rtc: snvs: Allow a time difference on clock register read 2022-11-15 21:25:44 +01:00
rtc-spear.c rtc: spear: Convert to platform remove callback returning void 2023-03-17 23:03:18 +01:00
rtc-st-lpc.c rtc: st-lpc: Simplify clk handling in st_rtc_probe() 2023-06-26 00:53:19 +02:00
rtc-starfire.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-stk17ta8.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-stm32.c rtc: stm32: remove incorrect #ifdef check 2023-08-10 09:22:04 +02:00
rtc-stmp3xxx.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-sun4v.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-sun6i.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-sunplus.c rtc: sunplus: Clean up redundant dev_err_probe() 2023-08-10 09:35:28 +02:00
rtc-sunxi.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-tegra.c rtc: tegra: Convert to platform remove callback returning void 2023-03-17 23:03:18 +01:00
rtc-test.c rtc: test: remove debug message 2020-12-03 23:43:23 +01:00
rtc-ti-k3.c rtc: Explicitly include correct DT includes 2023-07-27 23:31:29 +02:00
rtc-tps6586x.c rtc: tps6586x: Convert to platform remove callback returning void 2023-03-17 23:03:18 +01:00
rtc-tps65910.c rtc: tps65910: Correct driver module alias 2021-08-17 23:36:22 +02:00
rtc-twl.c rtc: twl: Convert to platform remove callback returning void 2023-03-17 23:03:18 +01:00
rtc-vt8500.c rtc: vt8500: Convert to platform remove callback returning void 2023-03-17 23:03:18 +01:00
rtc-wilco-ec.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-wm831x.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-wm8350.c rtc: wm8350: Convert to platform remove callback returning void 2023-03-17 23:03:18 +01:00
rtc-x1205.c rtc: Switch i2c drivers back to use .probe() 2023-06-06 23:29:37 +02:00
rtc-xgene.c rtc: xgene: Convert to platform remove callback returning void 2023-03-17 23:03:18 +01:00
rtc-zynqmp.c rtc: zynqmp: Convert to platform remove callback returning void 2023-03-17 23:03:19 +01:00
sysfs.c rtc: Include <linux/kstrtox.h> when appropriate 2022-11-15 21:01:51 +01:00