Date:   Tue, 21 Mar 2023 07:59:24 -0500
From:   Nishanth Menon <nm@ti.com>
To:     Dhruva Gole <d-gole@ti.com>
CC:     Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        <linux-kernel@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        Tero Kristo <kristo@kernel.org>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Julien Panis <jpanis@baylibre.com>, <bb@ti.com>
Subject: Re: [PATCH V3 1/2] arm64: dts: ti: k3-am62-wakeup: Introduce RTC node
Message-ID: <20230321125924.23ythtji67y66hsi@satisfied>
References: <20230320165123.80561-1-nm@ti.com>
 <20230320165123.80561-2-nm@ti.com>
 <4a1f33bb-882a-ed49-9e0e-b463203e0ea9@ti.com>
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On 10:07-20230321, Dhruva Gole wrote:
[...]

> 
> I was just wondering why some of the rtctests show failures on this platform:
> 
> https://gist.github.com/DhruvaG2000/5c6d8bb99b087308b916985d70f0c440
> 
> pass:5 fail:2
> 
> the test is compiled from tools/testing/selftests/rtc/rtctest.c for arm64 target
> 
> Is this expected?

I used the standard defconfig and [1] on beagleplay and
cross verified on 6.3-rc3 as well. It works fine. See logs below.

NOTE: BeaglePlay has a external 32k crystal that drives RTC and other
32k clock sources internal to the SoC. This helps maintain accurate
time. If your platform does'nt have an external 32k crystal OR AM62
does'nt enable 32k using MCU_CTRL_LFXOSC_CTRL[2], then default 32k RC
osc inside the SoC triggers. This internal clock is very variable.
There are a ton of stuff inside the SoC that depends on 32k, so this
wont be just a RTC specific behavior.

ti-next: (6.3-rc1)
ti-next + 6.3-rc3: (dirty is because of a rtctest Makefile mod to build
static)
https://gist.github.com/nmenon/e1b300652ac452ad55fa4cf936fc3e63


[1] https://git.kernel.org/pub/scm/linux/kernel/git/ti/linux.git/log/
[2] https://git.beagleboard.org/beagleplay/u-boot/-/blob/lc-ti-u-boot-2021.01/board/ti/am62x/evm.c#L243
-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D