Subject: Re: [PATCHv1 0/3] Enable RTC on Odroid N2

From: Kevin Hilman <[email-masked]>
Date: Thu, 16 Jul 2020 14:28:58 -0700

Neil Armstrong <[email-masked]> writes:

> Hi,
>
> On 16/07/2020 10:20, Neil Armstrong wrote:
>> Hi,
>> 
>> On 16/07/2020 10:14, Anand Moon wrote:
>>> Hi Neil,
>>>
>>> Thanks for your review comments.
>>>
>>> On Thu, 16 Jul 2020 at 12:35, Neil Armstrong <[email-masked]> wrote:
>>>>
>>>> Hi Anand,
>>>>
>>>> Only the vrtc is able to wakeup the device from suspend,
>>>> the external RTC is not capable.
>>>>
>>>> Neil
>>>
>>> Now I have two RTC driver registered
>>>
>>> $ dmesg | grep rtc
>>> [    4.737315] rtc-pcf8563 0-0051: registered as rtc0
>>> [    4.738763] rtc-pcf8563 0-0051: setting system clock to
>>> 2020-07-16T08:00:46 UTC (1594886446)
>>> [    4.790206] meson-vrtc ff8000a8.rtc: registered as rtc1
>>>
>>> And there are two nodes
>>> # ls /dev/rtc*
>>> /dev/rtc  /dev/rtc0  /dev/rtc1
>>>
>>> So it seames an issue that /dev/rtc0 is not able to handle wakeup events.
>>> How can we resolve this issue?
>>>
>>> # time rtcwake -s 30 -m mem
>>> rtcwake: /dev/rtc0 not enabled for wakeup events
>> 
>> rtcwake -d /dev/rtc1 -s 30 -m mem
>> 
>> As Christian reported off-list, it may be necessary to keep the vrtc as rtc0,
>> so you should add aliases in the odroid-n2 DT to have vrtc as rtc0 and the on-board
>> rtc as rtc1, but it may break the hwclock tools, so the reverse may be better
>> but you'll need to specify rtc1 to rtcwake.
>
> While looking closer to the Odroid-N2 schematics and U-Boot/SCP Firmware, the external on-board
> RTC can wake the device with the GPIO_AO 7, and wakeup is enabled in:
> https://github.com/hardkernel/u-boot/blob/odroidn2-v2015.01/board/hardkernel/odroidn2/firmware/scp_task/pwr_ctrl.c#L143
>
> So, something must be missing.

A couple possibilities come to mind (without looking at the specific RTC
driver):

1) pinctrl for that GPIO needs proper settings
2) DT node for the RTC needs "wakeup-source" property

Kevin

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