Re: [PATCH v2 07/15] parisc: use legacy_timer_tick

Helge Deller
2020-10-30T17:13:04Z

On 10/30/20 4:17 PM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> parisc has selected CONFIG_GENERIC_CLOCKEVENTS since commit 43b1f6abd590
> ("parisc: Switch to generic sched_clock implementation"), but does not
> appear to actually be using it, and instead calls the low-level
> timekeeping functions directly.

Arnd, thank you for this patch!
It reminded me that I really missed to fully implement the clockevents on parisc!

Your other patch ("RFC: m68k: mac: convert to generic clockevent")
was a big help too, as it showed how it might work on parisc as well.

Here is now a current version of the clockevents-enabling-patch for parisc:
https://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux.git/commit/?h=for-next&id=3b7ab4a74a2d1972dbeb33285d85f1500b2ff96a

> Remove the GENERIC_CLOCKEVENTS select again, and instead convert to
> the newly added legacy_timer_tick() helper.

My patch still needs more testing, but if it turns to work
out right, would you mind to drop your patch for parisc?

Helge

> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> Documentation/features/time/clockevents/arch-support.txt | 2 +-
> arch/parisc/Kconfig | 2 +-
> arch/parisc/kernel/time.c | 9 +++------
> 3 files changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/Documentation/features/time/clockevents/arch-support.txt b/Documentation/features/time/clockevents/arch-support.txt
> index 8287b6aa522e..61a5c9d68c15 100644
> --- a/Documentation/features/time/clockevents/arch-support.txt
> +++ b/Documentation/features/time/clockevents/arch-support.txt
> @@ -21,7 +21,7 @@
> | nds32: | ok |
> | nios2: | ok |
> | openrisc: | ok |
> - | parisc: | ok |
> + | parisc: | TODO |
> | powerpc: | ok |
> | riscv: | ok |
> | s390: | ok |
> diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
> index b234e8154cbd..78b17621ee4a 100644
> --- a/arch/parisc/Kconfig
> +++ b/arch/parisc/Kconfig
> @@ -52,7 +52,7 @@ config PARISC
> select HAVE_REGS_AND_STACK_ACCESS_API
> select GENERIC_SCHED_CLOCK
> select HAVE_UNSTABLE_SCHED_CLOCK if SMP
> - select GENERIC_CLOCKEVENTS
> + select LEGACY_TIMER_TICK
> select CPU_NO_EFFICIENT_FFS
> select NEED_DMA_MAP_STATE
> select NEED_SG_DMA_LENGTH
> diff --git a/arch/parisc/kernel/time.c b/arch/parisc/kernel/time.c
> index 13d94f0f94a0..08e4d480abe1 100644
> --- a/arch/parisc/kernel/time.c
> +++ b/arch/parisc/kernel/time.c
> @@ -70,8 +70,6 @@ irqreturn_t __irq_entry timer_interrupt(int irq, void *dev_id)
> /* gcc can optimize for "read-only" case with a local clocktick */
> unsigned long cpt = clocktick;
>
> - profile_tick(CPU_PROFILING);
> -
> /* Initialize next_tick to the old expected tick time. */
> next_tick = cpuinfo->it_value;
>
> @@ -86,10 +84,9 @@ irqreturn_t __irq_entry timer_interrupt(int irq, void *dev_id)
> cpuinfo->it_value = next_tick;
>
> /* Go do system house keeping. */
> - if (cpu == 0)
> - xtime_update(ticks_elapsed);
> -
> - update_process_times(user_mode(get_irq_regs()));
> + if (cpu != 0)
> + ticks_elapsed = 0;
> + legacy_timer_tick(ticks_elapsed);
>
> /* Skip clockticks on purpose if we know we would miss those.
> * The new CR16 must be "later" than current CR16 otherwise
>