From: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
To: Alexandre Belloni <alexandre.belloni@bootlin.com>,
Sam Protsenko <semen.protsenko@linaro.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>,
linux-rtc@vger.kernel.org, linux-samsung-soc@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/4] rtc: s3c: Fix RTC read on first boot
Date: Tue, 19 Oct 2021 18:10:15 +0200 [thread overview]
Message-ID: <9206176d-2a79-a70d-9b2e-546385b42f3b@canonical.com> (raw)
In-Reply-To: <YW7o4iVhJNmv/ea6@piout.net>
On 19/10/2021 17:48, Alexandre Belloni wrote:
> On 19/10/2021 16:17:24+0300, Sam Protsenko wrote:
>> On first RTC boot it has the month register value set to 0.
>> Unconditional subtracting of 1 subsequently in s3c_rtc_gettime() leads
>> to the next error message in kernel log:
>>
>> hctosys: unable to read the hardware clock
>>
>> That happens in s3c_rtc_probe() when trying to register the RTC, which
>> in turn tries to read and validate the time. Initialize RTC date/time
>> registers to valid values in probe function on the first boot to prevent
>> such errors.
>>
>
> No, never ever do that, the time is bogus and it has to stay this way,
> else userspace can't know whether the time on the RTC is the actual wall
> time or just some random value that you have set from the driver.
>
Indeed. This looks basically like a revert of your commit 5c78cceeb2d8
("rtc: s3c: stop setting bogus time"). For the Samsung PMIC RTC, we
dropped time initialization in commit fe787a5b2297 ("rtc: s5m: remove
undocumented time init on first boot").
Best regards,
Krzysztof
prev parent reply other threads:[~2021-10-19 16:10 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-19 13:17 [PATCH 0/4] rtc: s3c: S3C driver improvements Sam Protsenko
2021-10-19 13:17 ` [PATCH 1/4] rtc: s3c: Remove usage of devm_rtc_device_register() Sam Protsenko
2021-10-19 16:11 ` Krzysztof Kozlowski
2021-10-19 13:17 ` [PATCH 2/4] rtc: s3c: Add time range Sam Protsenko
2021-10-19 16:17 ` Krzysztof Kozlowski
2021-10-19 16:22 ` Krzysztof Kozlowski
2021-10-19 16:35 ` Sam Protsenko
2021-10-19 17:48 ` Alexandre Belloni
2021-10-19 19:12 ` Sam Protsenko
2021-10-19 21:04 ` Alexandre Belloni
2021-10-20 6:29 ` Krzysztof Kozlowski
2021-10-21 19:48 ` Sam Protsenko
2021-10-21 20:55 ` Alexandre Belloni
2021-10-19 16:20 ` Alexandre Belloni
2021-10-19 16:31 ` Sam Protsenko
2021-10-19 17:46 ` Alexandre Belloni
2021-10-19 13:17 ` [PATCH 3/4] rtc: s3c: Extract read/write IO into separate functions Sam Protsenko
2021-10-19 16:24 ` Krzysztof Kozlowski
2021-10-19 13:17 ` [PATCH 4/4] rtc: s3c: Fix RTC read on first boot Sam Protsenko
2021-10-19 15:48 ` Alexandre Belloni
2021-10-19 16:04 ` Sam Protsenko
2021-10-19 16:19 ` Krzysztof Kozlowski
2021-10-19 16:10 ` Krzysztof Kozlowski [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=9206176d-2a79-a70d-9b2e-546385b42f3b@canonical.com \
--to=krzysztof.kozlowski@canonical.com \
--cc=a.zummo@towertech.it \
--cc=alexandre.belloni@bootlin.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-rtc@vger.kernel.org \
--cc=linux-samsung-soc@vger.kernel.org \
--cc=semen.protsenko@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.