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rtc: Extend timeout for waiting for UIP to clear to 1s
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Specs don't say anything about UIP being cleared within 10ms. They
only say that UIP won't occur for another 244uS. If a long NMI occurs
while UIP is still updating it might not be possible to get valid
data in 10ms.

This has been observed in the wild that around s2idle some calls can
take up to 480ms before UIP is clear.

Adjust callers from outside an interrupt context to wait for up to a
1s instead of 10ms.

Cc:  <stable@vger.kernel.org> # 6.1.y
Fixes: ec5895c ("rtc: mc146818-lib: extract mc146818_avoid_UIP")
Reported-by: Carsten Hatger <xmb8dsv4@gmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217626
Tested-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Reviewed-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Acked-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20231128053653.101798-5-mario.limonciello@amd.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Mario Limonciello authored and Alexandre Belloni committed Dec 17, 2023
1 parent 120931d commit cef9ecc
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Showing 4 changed files with 4 additions and 4 deletions.
2 changes: 1 addition & 1 deletion arch/x86/kernel/rtc.c
Original file line number Diff line number Diff line change
Expand Up @@ -67,7 +67,7 @@ void mach_get_cmos_time(struct timespec64 *now)
return;
}

if (mc146818_get_time(&tm, 10)) {
if (mc146818_get_time(&tm, 1000)) {
pr_err("Unable to read current time from RTC\n");
now->tv_sec = now->tv_nsec = 0;
return;
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2 changes: 1 addition & 1 deletion drivers/base/power/trace.c
Original file line number Diff line number Diff line change
Expand Up @@ -120,7 +120,7 @@ static unsigned int read_magic_time(void)
struct rtc_time time;
unsigned int val;

if (mc146818_get_time(&time, 10) < 0) {
if (mc146818_get_time(&time, 1000) < 0) {
pr_err("Unable to read current time from RTC\n");
return 0;
}
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2 changes: 1 addition & 1 deletion drivers/rtc/rtc-cmos.c
Original file line number Diff line number Diff line change
Expand Up @@ -231,7 +231,7 @@ static int cmos_read_time(struct device *dev, struct rtc_time *t)
if (!pm_trace_rtc_valid())
return -EIO;

ret = mc146818_get_time(t, 10);
ret = mc146818_get_time(t, 1000);
if (ret < 0) {
dev_err_ratelimited(dev, "unable to read current time\n");
return ret;
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2 changes: 1 addition & 1 deletion drivers/rtc/rtc-mc146818-lib.c
Original file line number Diff line number Diff line change
Expand Up @@ -93,7 +93,7 @@ EXPORT_SYMBOL_GPL(mc146818_avoid_UIP);
*/
bool mc146818_does_rtc_work(void)
{
return mc146818_avoid_UIP(NULL, 10, NULL);
return mc146818_avoid_UIP(NULL, 1000, NULL);
}
EXPORT_SYMBOL_GPL(mc146818_does_rtc_work);

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