From: Stefan Herbrechtsmeier <stefan.herbrechtsmeier-oss@weidmueller.com>
To: Stefan Roese <sr@denx.de>, Tony Dinh <mibodhi@gmail.com>,
Simon Glass <sjg@chromium.org>
Cc: "U-Boot Mailing List" <u-boot@lists.denx.de>,
"Pali Rohár" <pali@kernel.org>,
"Michael Walle" <michael@walle.cc>
Subject: Re: [PATCH 0/6] Enable CONFIG_TIMER for all Kirwood / MVEBU boards
Date: Thu, 1 Sep 2022 13:52:38 +0200 [thread overview]
Message-ID: <11acb481-bc4a-0d75-910b-e3e2f3228645@weidmueller.com> (raw)
In-Reply-To: <f94dd6e8-98f5-85d5-6e14-f3dbcd9d69f3@denx.de>
Hi,
Am 01.09.2022 um 11:27 schrieb Stefan Roese:
> Hi Tony,
>
> On 01.09.22 09:39, Tony Dinh wrote:
>
> <snip>
>
>>>> Some ideas.
>>>>
>>>> The get_timer() function looks wrong assigning an uint64_t to ulong.
>>>>
>>>> lib/time.c
>>>>
>>>> static uint64_t notrace tick_to_time(uint64_t tick)
>>>> uint64_t notrace get_ticks(void)
>>>> uint64_t __weak notrace get_ticks(void)
>>>>
>>>> ulong __weak get_timer(ulong base)
>>>> {
>>>> return tick_to_time(get_ticks()) - base;
>>>> }
>>>>
>>>> Most of the timer infrastructure is using uint64_t. I'm seeing this
>>>> __weak function get_timer was invoked in Kirkwood boards. Both in
>>>> sleep and timer commands.
>>>
>>> The get_ticks() thing can run at 1MHz but the timer is 1KHz, so that
>>> is why we don't need a u64 for the timer.
>>
>> Thanks for your explanation! However, would you agree that code is
>> problematic and needed some improvement ? IOW, depending what the
>> compiler does, it might return the 1st 32 bit of the 64-bit integer
>> result?
>
> It will return the lower 32 bits if the system is 32bit, yes.
>
> To check if we have a problem here, please add this (totally untested)
> code and extend it if it makes sense:
>
> diff --git a/lib/time.c b/lib/time.c
> index bbf191f67323..ef5252419f3b 100644
> --- a/lib/time.c
> +++ b/lib/time.c
> @@ -146,7 +146,15 @@ int __weak timer_init(void)
> /* Returns time in milliseconds */
> ulong __weak get_timer(ulong base)
> {
> - return tick_to_time(get_ticks()) - base;
> + u64 ticks = get_ticks();
> + u64 time_ms = tick_to_time(ticks);
> +
> + if (time_ms & 0xffffffff00000000ULL)
> + printf("ticks=%lld time_ms=%lld\n", ticks, time_ms);
> + if ((time_ms - base) & 0xffffffff80000000ULL)
> + printf("ticks=%lld time_ms=%lld base=%ld ret=%lld\n",
> ticks, time_ms, base, time_ms - base);
> +
> + return time_ms - base;
> }
>
> At least here, you seem to have a wrap around with the 32bits AFAICT:
>
>> 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.
>
> 4294952265 = 0xFFFFC549!
>
Does the driver use a 32 bit counter without the timer_conv_64 function
inside the get_count function?
Regards
Stefan
next prev parent reply other threads:[~2022-09-01 11:52 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-30 11:53 [PATCH 0/6] Enable CONFIG_TIMER for all Kirwood / MVEBU boards Stefan Roese
2022-08-30 11:53 ` [PATCH 1/6] timer: orion-timer: Add support for other Armada SoC's Stefan Roese
2022-08-30 11:53 ` [PATCH 2/6] timer: orion-timer: Add timer_get_boot_us() for BOOTSTAGE support Stefan Roese
2022-08-30 12:00 ` Michael Walle
2022-08-30 12:08 ` Stefan Roese
2022-08-30 15:56 ` Simon Glass
2022-08-31 5:57 ` Stefan Roese
2022-08-31 17:44 ` Simon Glass
2022-09-01 5:33 ` Stefan Roese
2022-08-30 11:53 ` [PATCH 3/6] arm: mvebu: Use CONFIG_TIMER on all MVEBU & KIRKWOOD platforms Stefan Roese
2022-08-30 12:04 ` Michael Walle
2022-08-30 12:11 ` Stefan Roese
2022-08-30 11:53 ` [PATCH 4/6] arm: mvebu: dts: Makefile: Compile Armada 375 dtb in a separate step Stefan Roese
2022-08-30 11:53 ` [PATCH 5/6] arm: mvebu: dts: armada-375.dtsi: Add timer0 & timer1 Stefan Roese
2022-08-30 11:53 ` [PATCH 6/6] arm: mvebu: dts: mvebu-u-boot.dtsi: Add "u-boot, dm-pre-reloc" to timer DT node Stefan Roese
2022-08-30 22:15 ` [PATCH 0/6] Enable CONFIG_TIMER for all Kirwood / MVEBU boards Tony Dinh
2022-08-31 5:02 ` Stefan Roese
2022-08-31 5:08 ` Stefan Roese
2022-08-31 6:12 ` Stefan Roese
2022-08-31 6:45 ` Tony Dinh
2022-08-31 6:30 ` Tony Dinh
2022-08-31 7:22 ` Stefan Roese
2022-08-31 15:08 ` Tony Dinh
2022-08-31 21:53 ` Tony Dinh
2022-09-01 1:38 ` Tony Dinh
2022-09-01 2:27 ` Simon Glass
2022-09-01 7:39 ` Tony Dinh
2022-09-01 9:27 ` Stefan Roese
2022-09-01 11:52 ` Stefan Herbrechtsmeier [this message]
2022-09-02 5:38 ` Stefan Roese
2022-09-01 14:34 ` Simon Glass
2022-09-01 23:46 ` Tony Dinh
2022-09-02 2:51 ` Tony Dinh
2022-09-02 3:49 ` Tony Dinh
2022-09-16 4:34 Stefan Roese
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