linux-kernel - Re: [PATCH 4/4] rtc: Extend timeout for waiting for UIP to clear to 1s

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Message-ID: <c6c678c1-bd75-4fb2-bf51-e1a745a62a2d@o2.pl>
Date:   Sat, 18 Nov 2023 20:25:47 +0100
From:   Mateusz Jończyk <mat.jonczyk@...pl>
To:     Mario Limonciello <mario.limonciello@....com>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     "open list:REAL TIME CLOCK (RTC) SUBSYSTEM" 
        <linux-rtc@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        linux-pm@...r.kernel.org, tobrohl@...il.com, aalsing@...il.com,
        Dhaval.Giani@....com, xmb8dsv4@...il.com, x86@...nel.org
Subject: Re: [PATCH 4/4] rtc: Extend timeout for waiting for UIP to clear to
 1s

W dniu 17.11.2023 o 07:32, Mario Limonciello pisze:
> 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.
>
> Reported-by: xmb8dsv4@...il.com
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217626
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
>  arch/x86/kernel/rtc.c          | 2 +-
>  drivers/base/power/trace.c     | 2 +-
>  drivers/rtc/rtc-cmos.c         | 2 +-
>  drivers/rtc/rtc-mc146818-lib.c | 2 +-
>  4 files changed, 4 insertions(+), 4 deletions(-)

Consider:

Fixes: ec5895c0f2d8 ("rtc: mc146818-lib: extract mc146818_avoid_UIP")

If you would like to Cc: stable this patch,

commit d2a632a8a117 ("rtc: mc146818-lib: reduce RTC_UIP polling period")

is a prerequisite.

Greetings,

Mateusz