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

[Gavin Hu (Arm Technology China)]

Hi Jerin,

> -----Original Message-----
> From: Jerin Jacob <jerinjacobk at gmail.com>
> Sent: Wednesday, September 11, 2019 8:27 PM
> To: Gavin Hu (Arm Technology China) <Gavin.Hu at arm.com>
> Cc: dev at dpdk.org; nd <nd at arm.com>; thomas at monjalon.net;
> stephen at networkplumber.org; jerinj at marvell.com; Pavan Nikhilesh
> <pbhagavatula at marvell.com>; Honnappa Nagarahalli
> <Honnappa.Nagarahalli at arm.com>
> Subject: Re: [dpdk-dev] [PATCH v4 2/6] eal: add the APIs to wait until equal
> 
> On Thu, Aug 22, 2019 at 11:43 AM Gavin Hu <gavin.hu at 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 at arm.com>
> > Reviewed-by: Ruifeng Wang <ruifeng.wang at arm.com>
> > Reviewed-by: Steve Capper <steve.capper at arm.com>
> > Reviewed-by: Ola Liljedahl <ola.liljedahl at arm.com>
> > Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli at arm.com>
> > Reviewed-by: Phil Yang <phil.yang at arm.com>
> > Acked-by: Pavan Nikhilesh <pbhagavatula at 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
Thanks for pointing out this, I will fix this in next version. 
> 
> /**
>  * Doxygen comment
>  */
> rte_wait_until_equal_relaxed_16(..)
> {
>         __WAIT_UNTIL_EQUAL(..)
> }
Following the other examples, just add some declarations of the APIs in the beginning of the file, with the Doxygen comments above can fix this problem.
The implementations of the APIs do not need to change, please help review the v5 version.