On Tue 2025-11-11 13:20:01, Andy Shevchenko wrote:
> A handful drivers want to print a content of the struct timespec64
> in a format of %lld:%09ld. In order to make their lives easier, add
> the respecting specifier directly to the printf() implementation.
>
> Signed-off-by: Andy Shevchenko <[email protected]>
> ---
> Documentation/core-api/printk-formats.rst | 11 ++++++++--
> lib/tests/printf_kunit.c | 4 ++++
> lib/vsprintf.c | 25 +++++++++++++++++++++++
> 3 files changed, 38 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/core-api/printk-formats.rst
> b/Documentation/core-api/printk-formats.rst
> index 7f2f11b48286..c0b1b6089307 100644
> --- a/Documentation/core-api/printk-formats.rst
> +++ b/Documentation/core-api/printk-formats.rst
> @@ -547,11 +547,13 @@ Time and date
> %pt[RT]s YYYY-mm-dd HH:MM:SS
> %pt[RT]d YYYY-mm-dd
> %pt[RT]t HH:MM:SS
> - %pt[RT][dt][r][s]
> + %ptSp <seconds>.<nanoseconds>
I know that that there was no good choice. But I am curious.
Does the 'p' stands for some particular word, for example, "plain" ?
I do not want to start bike shedding but I think about
using 'n' as "number".
> + %pt[RST][dt][r][s]
>
> For printing date and time as represented by::
>
> - R struct rtc_time structure
> + R content of struct rtc_time
> + S content of struct timespec64
> T time64_t type
>
> in human readable format.
> @@ -563,6 +565,11 @@ The %pt[RT]s (space) will override ISO 8601 separator by
> using ' ' (space)
> instead of 'T' (Capital T) between date and time. It won't have any effect
> when date or time is omitted.
>
> +The %ptSp is equivalent to %lld.%09ld for the content of the struct
> timespec64.
> +When the other specifiers are given, it becomes the respective equivalent of
> +%ptT[dt][r][s].%09ld. In other words, the seconds are being printed in
> +the human readable format followed by a dot and nanoseconds.
> +
> Passed by reference.
>
> struct clk
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index 3f99834fd788..fdd06e8957a3 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -2464,6 +2488,7 @@ early_param("no_hash_pointers",
> no_hash_pointers_enable);
> * - 'g' For block_device name (gendisk + partition number)
> * - 't[RT][dt][r][s]' For time and date as represented by:
We should add 'S' here as well:
* - 't[RST][dt][r][s]' For time and date as represented by:
That said, I am not sure about the optional '[p]'. We could
either do:
* - 't[RST][p][dt][r][s]' For time and date as represented by:
or
* - 'tSp' For time represented by struct timespec64 printed
as seconds.nanoseconds
* - 't[RST][dt][r][s]' For time and date as represented by:
> * R struct rtc_time
> + * S struct timespec64
> * T time64_t
> * - 'C' For a clock, it prints the name (Common Clock Framework) or address
> * (legacy clock framework) of the clock
Otherwise, it looks good.
Best Regards,
Petr
