Re: [PATCH v2] clocksource/drivers/riscv: Get rid of clocksource_arch_init() callback

From: Samuel Holland
Date: Tue Jan 03 2023 - 12:39:39 EST


On 12/29/22 16:46, Prabhakar wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
>
> Having a clocksource_arch_init() callback always sets vdso_clock_mode to
> VDSO_CLOCKMODE_ARCHTIMER if GENERIC_GETTIMEOFDAY is enabled, this is
> required for the riscv-timer.
>
> This works for platforms where just riscv-timer clocksource is present.
> On platforms where other clock sources are available we want them to
> register with vdso_clock_mode set to VDSO_CLOCKMODE_NONE.
>
> On the Renesas RZ/Five SoC OSTM block can be used as clocksource [0], to
> avoid multiple clock sources being registered as VDSO_CLOCKMODE_ARCHTIMER
> move setting of vdso_clock_mode in the riscv-timer driver instead of doing
> this in clocksource_arch_init() callback as done similarly for ARM/64
> architecture.
>
> [0] drivers/clocksource/renesas-ostm.c
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> Tested-by: Samuel Holland <samuel@xxxxxxxxxxxx>
> ---
> RFC -> v2
> * Dropped vdso_default static global variable
> * Used IS_ENABLED() macro
> * Included Tested-by from Samuel
>
> RFC:
> https://patchwork.kernel.org/project/linux-renesas-soc/patch/20221211215843.24024-1-prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx/
> ---
> arch/riscv/Kconfig | 1 -
> arch/riscv/kernel/time.c | 9 ---------
> drivers/clocksource/timer-riscv.c | 5 +++++
> 3 files changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index e2b656043abf..9c687da7756d 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -12,7 +12,6 @@ config 32BIT
>
> config RISCV
> def_bool y
> - select ARCH_CLOCKSOURCE_INIT
> select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
> select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
> select ARCH_HAS_BINFMT_FLAT
> diff --git a/arch/riscv/kernel/time.c b/arch/riscv/kernel/time.c
> index 8217b0f67c6c..42bee305e997 100644
> --- a/arch/riscv/kernel/time.c
> +++ b/arch/riscv/kernel/time.c
> @@ -30,12 +30,3 @@ void __init time_init(void)
> of_clk_init(NULL);
> timer_probe();
> }
> -
> -void clocksource_arch_init(struct clocksource *cs)
> -{
> -#ifdef CONFIG_GENERIC_GETTIMEOFDAY
> - cs->vdso_clock_mode = VDSO_CLOCKMODE_ARCHTIMER;
> -#else
> - cs->vdso_clock_mode = VDSO_CLOCKMODE_NONE;
> -#endif
> -}
> diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c
> index 55dad7965f43..c416e5e934bf 100644
> --- a/drivers/clocksource/timer-riscv.c
> +++ b/drivers/clocksource/timer-riscv.c
> @@ -77,6 +77,11 @@ static struct clocksource riscv_clocksource = {
> .mask = CLOCKSOURCE_MASK(64),
> .flags = CLOCK_SOURCE_IS_CONTINUOUS,
> .read = riscv_clocksource_rdtime,
> +#if IS_ENABLED(CONFIG_GENERIC_GETTIMEOFDAY)
> + .vdso_clock_mode = VDSO_CLOCKMODE_ARCHTIMER,
> +#else
> + .vdso_clock_mode = VDSO_CLOCKMODE_NONE,

The else case isn't strictly necessary because VDSO_CLOCKMODE_NONE is
the default. Either way it looks fine to me.

Reviewed-by: Samuel Holland <samuel@xxxxxxxxxxxx>

And I tested v2 as well.

Regards,
Samuel

> +#endif
> };
>
> static int riscv_timer_starting_cpu(unsigned int cpu)