[PATCH 0/6] Enable CONFIG_TIMER for all Kirwood / MVEBU boards

Tony Dinh mibodhi at gmail.com
Wed Aug 31 23:53:55 CEST 2022 

Hi Stefan,

On Wed, Aug 31, 2022 at 8:08 AM Tony Dinh <mibodhi at gmail.com> wrote:
>
> Hi Stefan,
>
> On Wed, Aug 31, 2022 at 12:22 AM Stefan Roese <sr at denx.de> wrote:
> >
> > Hi Tony,
> >
> > On 31.08.22 08:30, Tony Dinh wrote:
> > > Hi Stefan,
> > >
> > > On Tue, Aug 30, 2022 at 10:08 PM Stefan Roese <sr at denx.de> wrote:
> > >>
> > >> Hi Tony,
> > >>
> > >> On 31.08.22 07:02, Stefan Roese wrote:
> > >>> Hi Tony,
> > >>>
> > >>> On 31.08.22 00:15, Tony Dinh wrote:
> > >>>> Hi Stefan,
> > >>>>
> > >>>> On Tue, Aug 30, 2022 at 4:53 AM Stefan Roese <sr at denx.de> wrote:
> > >>>>>
> > >>>>> This patchset enhaces the recently added Orion Timer driver to support
> > >>>>> all other Kirkwood & 32bit MVEBU Armada platforms. Additionally, this
> > >>>>> timer support is then enabled per default for those platforms, so that
> > >>>>> the board config files don't need to be changed. Also necessary is
> > >>>>> some dts hacking, so that the timer DT node is available in early
> > >>>>> U-Boot stages.
> > >>>>>
> > >>>>> I've successfully tested this patchset on an Armada XP board. Additional
> > >>>>> test on other boards and platforms are very welcome and necessary.
> > >>>>
> > >>>> I've run some tests with the following 2 Kirkwood boards: Cloud
> > >>>> Engines Pogo V4 88F6192 (with CONFIG_DM_RTC and CONFIG_RTC_EMULATION),
> > >>>> and Marvell Sheevaplug 88F6281 (with CONFIG_DM_RTC and CONFIG_RTC_MV).
> > >>>>
> > >>>> It seems that it was either frozen or the timer did not expire at some
> > >>>> subsequent sleep commands. Sometime it happened at 2nd command, some
> > >>>> time at a later sleep command. For example,
> > >>>>
> > >>>> === Pogo V4 (the 1st sleep command works correctly at 10 seconds on my
> > >>>> stopwatch)
> > >>>>
> > >>>> U-Boot 2022.10-rc3-00048-g66ccd87a9c-dirty (Aug 30 2022 - 13:38:24 -0700)
> > >>>> Pogoplug V4
> > >>>>
> > >>>> Hit any key to stop autoboot:  0
> > >>>> Pogo_V4> sleep 10
> > >>>> Pogo_V4> sleep 31.5
> > >>>> <frozen here>
> > >>>
> > >>> Does the cmd interface support fractial numbers? Please test again with
> > >>> 31 or other integral numbers.
> > >>>
> > >>>> === Sheevaplug (RTC battery is old, so the date was not updated, but
> > >>>> the clock seems OK)
> > >>>>
> > >>>> U-Boot 2022.10-rc3-00048-g66ccd87a9c-dirty (Aug 30 2022 - 14:14:24 -0700)
> > >>>> Marvell-Sheevaplug
> > >>>> Hit any key to stop autoboot:  0
> > >>>> => date
> > >>>> Date: 2000-01-01 (Saturday)    Time:  0:02:55
> > >>>> => sleep 10
> > >>>> => date
> > >>>> Date: 2000-01-01 (Saturday)    Time:  0:03:18
> > >>>> => sleep 10
> > >>>> => sleep 20.1
> > >>>> <frozen here>
> > >>>>
> > >>>> Please let me know what I can do (i.e. perhaps running a debug patch).
> > >>>
> > >>> Please see above. I assume that the fractional numbers result in very
> > >>> long numbers internally, which result in a frozen / hanging system.
> > >>
> > >> I just tested fractional numbers on another board and hey, it just
> > >> works. Learned something new. So we seem to have a problem here. Let
> > >> me see, if I can find something.
> > >
> > > I've added debug printfs and possibly tracked down this issue. Seems
> > > like in the 2nd call to sleep, get_timer(0) did not reset the start
> > > number.
> > >
> > > cmd/sleep.c
> > > static int do_sleep(struct cmd_tbl *cmdtp, int flag, int argc,
> > >                      char *const argv[])
> > > {
> > >         ulong start = get_timer(0);
> > >
> > > "do_sleep got a timer start = 2015" is the 1st call to sleep 5.
> > > "do_sleep got a timer start = 16304" is the 2nd call to sleep 10.
> > >
> > > <BEGIN log>
> > > Pogo_V4> sleep 5
> > > do_sleep got a timer start = 2015
> > > do_sleep delay = 5000
> > > do_sleep delay = 5000
> > > do_sleep sleeping...
> > > do_sleep start 2015 curent 100
> > > do_sleep start 2015 curent 200
> > > do_sleep start 2015 curent 300
> > > <snip>
> > > do_sleep start 2015 curent 4900
> > > do_sleep end of sleep ... current = 5000
> > > Pogo_V4>
> > >
> > > Pogo_V4> sleep 10
> > > do_sleep got a timer start = 16304
> > > do_sleep delay = 10000
> > > do_sleep delay = 10000
> > > do_sleep sleeping...
> > > <snip>
> > >
> > > <END log>
> > >
> > > So somewhere in the DM timer, "start" got accumulated. I think each
> > > get_timer(0) should be a different timer instance. It looks like the
> > > same timer instance is used again and again, causing the "start "to
> > > grow bigger, and at one point it might just overflow.
> >
> > Frankly I don't really understand the problem you describe above. What
> > do you mean with "timer instance"? get_timer(0) will return different
> > values, depending on when you call this function. So where exactly is
> > the problem with the 2nd "sleep 10" above?
>
> Please ignore what I said above! I misunderstood what get_timer()
> does. I'll try again on another KIrkwood  board to see if the behavior
> will be the same.

I've  run the tests again with the Seagate GoFlex Home board (Kirkwood
88F6281). Below is the log, with my annotated comments starting with
****.
In these tests,  current = get_timer(start) is inside the while loop.
And I printed out the start and current values when (current % 100 ==
0).

<BEGIN LOG>
U-Boot 2022.10-rc3-00048-g66ccd87a9c-dirty (Aug 31 2022 - 13:06:04 -0700)
Seagate GoFlex Home

SoC:   Kirkwood 88F6281_A1
DRAM:  128 MiB
Core:  12 devices, 10 uclasses, devicetree: separate
NAND:  orion_timer_probe successful
256 MiB
Loading Environment from NAND... OK
In:    serial
Out:   serial
Err:   serial
Net:   eth0: ethernet-controller at 72000
Hit any key to stop autoboot:  0

GoFlexHome> date
Date: 2022-08-31 (Wednesday)    Time: 20:43:03

GoFlexHome> sleep 5
do_sleep got a timer start = 1244
do_sleep delay = 5000
do_sleep delay = 5000
do_sleep sleeping...
do_sleep start 1244 current 100
<snip>
do_sleep start 1244 current 2300
<snip>
do_sleep start 1244 current 3700
<snip>
do_sleep start 1244 current 4800
do_sleep start 1244 current 4900
do_sleep end of sleep ... current = 5000

**** working as intended

GoFlexHome> sleep 10
do_sleep got a timer start = 11428
do_sleep delay = 10000
do_sleep delay = 10000
do_sleep sleeping...
do_sleep start 11428 current 100
<snip>
do_sleep start 11428 current 2300
<snip>
do_sleep start 11428 current 9900
do_sleep end of sleep ... current = 10000

**** working as intended

GoFlexHome> sleep 20.5
do_sleep got a timer start = 15031
do_sleep delay = 20000
do_sleep delay = 20500
do_sleep sleeping...
do_sleep start 15031 current 100
<snip>
do_sleep start 15031 current 6400
do_sleep end of sleep ... current = 4294952265

*** Something strange happened here. current should be 6500, but it
seems to have garbage. So the loop exits prematurely.

GoFlexHome> sleep 20.5
do_sleep got a timer start = 8339
do_sleep delay = 20000
do_sleep delay = 20500
do_sleep sleeping...
do_sleep start 8339 current 100
do_sleep start 8339 current 200
<snip>
do_sleep start 8339 current 12300
do_sleep start 8339 current 12400
do_sleep start 8339 current 12500
do_sleep start 8339 current 12600
do_sleep start 8339 current 12700
do_sleep start 8339 current 12800
do_sleep start 8339 current 12900
do_sleep start 8339 current 13000
do_sleep start 8339 current 13100

*** It was frozen right here. Control-C could not interrupt the loop,
so my guess
*** either it was stuck during the call to get_timer(). Or the current value
*** overflowed and crashed the system.

<END LOG>

Finally, I removed the patch set, and rerun the sleep tests on this
board. They all worked fine, I did not see anything strange.

Thanks,
Tony

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