linux-kernel - Fwd: Read from RTC broken upon resume from suspend on HP Pro x360 435 G9 w/ AMD Ryzen 7 5825U

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Date:   Mon, 3 Jul 2023 20:25:35 +0700
From:   Bagas Sanjaya <bagasdotme@...il.com>
To:     Mateusz Jończyk <mat.jonczyk@...pl>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Carsten Hatger <xmb8dsv4@...il.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Regressions <regressions@...ts.linux.dev>, x86@...nel.org
Subject: Fwd: Read from RTC broken upon resume from suspend on HP Pro x360 435
 G9 w/ AMD Ryzen 7 5825U

Hi,

I notice a regression report on Bugzilla [1]. Quoting from it:

> Dear all,
> 
> read access to the device's RTC fails upon resume from suspend with the following error message grabbed from the kernel ring buffer:
> 
> [409610.163139] Unable to read current time from RTC
> 
> The issue is rare and more likely to appear if the system has been in standby for more than 24hrs w/o interruption.
> 
> Same issue is reported to appear on HP Elite G9 devices, cf. https://bbs.archlinux.org/viewtopic.php?id=283620
> 
> The issue screws up the systems time resulting in erroneous dated log entries, failing authentication, ..., thus requiring a reboot.
> 
> Please see attached dmesg output (line 2069) for further information. 
> 
> AMD staff member suspected commit d2a632a8a11756197deb1341bbb09c09abaf20ce to cause a race condition, thus being responsible for the issue. They suggested to increase the delays introduced by latter commmit to 300us. Unfortunately this does not resolve the issue.
> 
> Any help would be appreciated.

See Bugzilla for the full thread and attached dmesg.

Mateusz: It looks like this regression is caused by a commit of yours.
Would you like to take a look on it?

Anyway, I'm adding it to regzbot:

#regzbot introduced: d2a632a8a11756 https://bugzilla.kernel.org/show_bug.cgi?id=217626
#regzbot title: reducing RTC_UIP polling period causes broken RTC on resume from suspend

Thanks.

[1]: https://bugzilla.kernel.org/show_bug.cgi?id=217626

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