Re: [dpdk-dev] [PATCH v4 2/6] eal: add the APIs to wait until equal

[Jerin Jacob <jerinjacobk@gmail.com>]

On Thu, Aug 22, 2019 at 11:43 AM Gavin Hu <gavin.hu@arm.com> wrote:
>
> The rte_wait_until_equalxx APIs abstract the functionality of 'polling
> for a memory location to become equal to a given value'.
>
> Signed-off-by: Gavin Hu <gavin.hu@arm.com>
> Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
> Reviewed-by: Steve Capper <steve.capper@arm.com>
> Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
> Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> Reviewed-by: Phil Yang <phil.yang@arm.com>
> Acked-by: Pavan Nikhilesh <pbhagavatula@marvell.com>
> ---
>  .../common/include/arch/arm/rte_pause_64.h         | 30 ++++++++++++++++++++++
>  lib/librte_eal/common/include/generic/rte_pause.h  | 26 ++++++++++++++++++-
>  2 files changed, 55 insertions(+), 1 deletion(-)
>
> diff --git a/lib/librte_eal/common/include/arch/arm/rte_pause_64.h b/lib/librte_eal/common/include/arch/arm/rte_pause_64.h
> index 93895d3..dabde17 100644
> --- a/lib/librte_eal/common/include/arch/arm/rte_pause_64.h
> +++ b/lib/librte_eal/common/include/arch/arm/rte_pause_64.h
> @@ -1,5 +1,6 @@
>  /* SPDX-License-Identifier: BSD-3-Clause
>   * Copyright(c) 2017 Cavium, Inc
> + * Copyright(c) 2019 Arm Limited
>   */
>
>  #ifndef _RTE_PAUSE_ARM64_H_
> @@ -17,6 +18,35 @@ static inline void rte_pause(void)
>         asm volatile("yield" ::: "memory");
>  }
>
> +#ifdef RTE_ARM_USE_WFE
> +#define __WAIT_UNTIL_EQUAL(name, asm_op, wide, type) \
> +static __rte_always_inline void \
> +rte_wait_until_equal_##name(volatile type * addr, type expected) \
> +{ \
> +       type tmp; \
> +       asm volatile( \
> +               #asm_op " %" #wide "[tmp], %[addr]\n" \
> +               "cmp    %" #wide "[tmp], %" #wide "[expected]\n" \
> +               "b.eq   2f\n" \
> +               "sevl\n" \
> +               "1:     wfe\n" \
> +               #asm_op " %" #wide "[tmp], %[addr]\n" \
> +               "cmp    %" #wide "[tmp], %" #wide "[expected]\n" \
> +               "bne    1b\n" \
> +               "2:\n" \
> +               : [tmp] "=&r" (tmp) \
> +               : [addr] "Q"(*addr), [expected] "r"(expected) \
> +               : "cc", "memory"); \
> +}
>
> +/* Wait for *addr to be updated with expected value */
> +__WAIT_UNTIL_EQUAL(relaxed_16, ldxrh, w, uint16_t)
> +__WAIT_UNTIL_EQUAL(acquire_16, ldaxrh, w, uint16_t)
> +__WAIT_UNTIL_EQUAL(relaxed_32, ldxr, w, uint32_t)
> +__WAIT_UNTIL_EQUAL(acquire_32, ldaxr, w, uint32_t)
> +__WAIT_UNTIL_EQUAL(relaxed_64, ldxr, x, uint64_t)
> +__WAIT_UNTIL_EQUAL(acquire_64, ldaxr, x, uint64_t)
>

This scheme doesn't allow to write Doxygen comments for the API
Please change to some scheme where you can Doxygen comments for each API
without code duplication. Something like

/**
 * Doxygen comment
 */
rte_wait_until_equal_relaxed_16(..)
{
        __WAIT_UNTIL_EQUAL(..)
}