Re: TS-219 RTC issue with Debian Buster

[Oliver Hartkopp <socketcan@hartkopp.net>]

Hello Uwe,

nice to read from you again :-)

I think I already solved the problem, see here:
https://marc.info/?l=linux-arm-kernel&m=156390875629259&w=2

Will file a Debian bug for it ...

Many thanks,
Oliver

On 23.07.19 21:06, Uwe Kleine-König wrote:
> Hello Oliver,
> 
> I added the RTC maintainers and list to Cc.
> 
> On Tue, Jul 23, 2019 at 05:30:48PM +0200, Oliver Hartkopp wrote:
>> I upgraded my TS-219 to Debian Buster with Kernel 4.19.0-5-marvell.
>>
>> They use dtbs/4.19.0-5-marvell/./kirkwood-ts219-6282.dtb
>>
>> Unfortunately the RTC doesn't seem to work.
>>
>> root@xxxxx:~# hwclock -v --test
>> hwclock from util-linux 2.33.1
>> System Time: 1563296223.425648
>> Trying to open: /dev/rtc0
>> Using the rtc interface to the clock.
>> Last drift adjustment done at 1563291472 seconds after 1969
>> Last calibration done at 1563291472 seconds after 1969
>> Hardware clock is on UTC time
>> Assuming hardware clock is kept in UTC time.
>> Waiting for clock tick...
>> hwclock: select() to /dev/rtc0 to wait for clock tick timed out
>> ...synchronization failed
>> Test mode: nothing was changed.
>> With strace the clock tick problem looks like this:
>>
>> write(1, "Waiting for clock tick...\n", 26Waiting for clock tick...
>> ) = 26
>> ioctl(4, RTC_UIE_ON)                    = 0
>> _newselect(5, [4], NULL, NULL, {tv_sec=10, tv_usec=0}) = 0 (Timeout)
>> write(2, "hwclock: ", 9hwclock: )                = 9
>> write(2, "select() to /dev/rtc0 to wait fo"..., 54select() to /dev/rtc0 to
>> wait for clock tick timed out) = 54
>> write(2, "\n", 1)                       = 1
>> ioctl(4, PHN_NOT_OH or RTC_UIE_OFF)     = 0
> 
> Maybe rtc-mv should set uie_unsupported if no irq is aquired?
> 
>> It looks the same with
>>
>> # hwclock --hctosys
>> hwclock: select() to /dev/rtc0 to wait for clock tick timed out
> 
> hwclock (from util-linux) is being stupid here. The tradtional RTC on
> the x86 platform has a resolution of 1s only and if you set it the next
> increment is 1 second after the last increment instead of 1 second after
> the new time was set. So hwclock waits for an update event and then sets
> the new time (in some cases to a tad later than requested) to ensure the
> PC clock is off by less than half a second. For most (if not all) other
> RTCs this is wrong and still worse if the RTC in question doesn't
> support UIE.
> 
>> I wonder whether the problem comes from a missing interrupt assignment
>>
>> rtc: rtc@10300 {
>>               compatible = "marvell,kirkwood-rtc", "marvell,orion-rtc";
>>               reg = <0x10300 0x20>;
>>               interrupts = <53>;            <- HERE!?!
>>               clocks = <&gate_clk 7>;
>>                 };
>>
>> ... I found in linux/arch/arm/boot/dts/kirkwood-6282.dtsi ?!?
>>
>> In /proc/interrupts there's no rtc assigned to an interrupt 53.
> 
> What is the output of dmesg | grep 10300 ?
>   
>> Accessing the rtc values (time/date) via /sys/class/rtc/rtc0 entries works
>> well and setting the date/time via "hwclock --systohc" does its job too. So
>> I2C and the rtc_s35390a driver seem to work so far.
> 
> You're not using the s35390a driver, do you?
>   
>> Any ideas why hwclock fails to work properly?
> 
> Try if
> 
> 	busybox hwclock
> 
> works better for you. At least this one doesn't have this strange PC
> quirk.
>   
> Best regards
> Uwe
>