Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'timers-urgent-2021-01-31' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fix from Thomas Gleixner:
"A fix for handling advertised, but non-existent 146818 RTCs correctly.
With the recent UIP handling changes the time readout of non-existent
RTCs hangs forever as the read returns always 0xFF which means the UIP
bit is set.
Sanity check the RTC before registering by checking the RTC_VALID
register for correctness"
* tag 'timers-urgent-2021-01-31' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
rtc: mc146818: Detect and handle broken RTCs
+15
+8
drivers/rtc/rtc-cmos.c
+8
drivers/rtc/rtc-cmos.c
···
805
805
806
806
spin_lock_irq(&rtc_lock);
807
807
808
+
/* Ensure that the RTC is accessible. Bit 0-6 must be 0! */
809
+
if ((CMOS_READ(RTC_VALID) & 0x7f) != 0) {
810
+
spin_unlock_irq(&rtc_lock);
811
+
dev_warn(dev, "not accessible\n");
812
+
retval = -ENXIO;
813
+
goto cleanup1;
814
+
}
815
+
808
816
if (!(flags & CMOS_RTC_FLAGS_NOFREQ)) {
809
817
/* force periodic irq to CMOS reset default of 1024Hz;
810
818
*
+7
drivers/rtc/rtc-mc146818-lib.c
+7
drivers/rtc/rtc-mc146818-lib.c
···
21
21
22
22
again:
23
23
spin_lock_irqsave(&rtc_lock, flags);
24
+
/* Ensure that the RTC is accessible. Bit 0-6 must be 0! */
25
+
if (WARN_ON_ONCE((CMOS_READ(RTC_VALID) & 0x7f) != 0)) {
26
+
spin_unlock_irqrestore(&rtc_lock, flags);
27
+
memset(time, 0xff, sizeof(*time));
28
+
return 0;
29
+
}
30
+
24
31
/*
25
32
* Check whether there is an update in progress during which the
26
33
* readout is unspecified. The maximum update time is ~2ms. Poll