linux-kernel - Re: [RFC PATCH 2/3] riscv: use VA+PA variant of CMO macros for DMA synchorization

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Message-ID: <CAJF2gTTO3jx8FqMVRmfgkjO02sCVx2SVbe-Sn1uKXojyn8RDaA@mail.gmail.com>
Date:   Wed, 4 Jan 2023 17:24:13 +0800
From:   Guo Ren <guoren@...nel.org>
To:     Icenowy Zheng <uwu@...nowy.me>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Heiko Stuebner <heiko@...ech.de>,
        Samuel Holland <samuel@...lland.org>,
        Conor Dooley <conor.dooley@...rochip.com>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 2/3] riscv: use VA+PA variant of CMO macros for DMA synchorization

On Wed, Jan 4, 2023 at 4:59 PM Icenowy Zheng <uwu@...nowy.me> wrote:
>
> 在 2023-01-04星期三的 16:50 +0800，Guo Ren写道：
> > On Wed, Jan 4, 2023 at 3:43 PM Icenowy Zheng <uwu@...nowy.me> wrote:
> > >
> > > DMA synchorization is done on PA and the VA is calculated from the
> > > PA.
> > >
> > > Use the alternative macro variant that takes both VA and PA as
> > > parameters, thus in case the ISA extension used support PA
> > > directly, the
> > > overhead for re-converting VA to PA can be omitted.
> > >
> > > Suggested-by: Guo Ren <guoren@...nel.org>
> > > Signed-off-by: Icenowy Zheng <uwu@...nowy.me>
> > > ---
> > >  arch/riscv/mm/dma-noncoherent.c | 8 ++++----
> > >  1 file changed, 4 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/arch/riscv/mm/dma-noncoherent.c b/arch/riscv/mm/dma-
> > > noncoherent.c
> > > index d919efab6eba..a751f4aece62 100644
> > > --- a/arch/riscv/mm/dma-noncoherent.c
> > > +++ b/arch/riscv/mm/dma-noncoherent.c
> > > @@ -19,13 +19,13 @@ void arch_sync_dma_for_device(phys_addr_t
> > > paddr, size_t size,
> > >
> > >         switch (dir) {
> > >         case DMA_TO_DEVICE:
> > > -               ALT_CMO_OP(clean, vaddr, size,
> > > riscv_cbom_block_size);
> > > +               ALT_CMO_OP_VPA(clean, vaddr, paddr, size,
> > > riscv_cbom_block_size);
> > ALT_CMO_OP -> ALT_CMO_OP_VPA, is the renaming necessary?
>
> I didn't rename the original ALT_CMO_OP, ALT_CMO_OP_VPA is something
> new.
The ##_VPA is really strange.

How about:
ALT_CMO_OP          -> ALT_CMO_OP_VA
ALT_CMO_OP_VPA -> ALT_CMO_OP

>
> >
> > Others:
> > Reviewed-by: Guo Ren <guoren@...nel.org>
> >
> > >                 break;
> > >         case DMA_FROM_DEVICE:
> > > -               ALT_CMO_OP(clean, vaddr, size,
> > > riscv_cbom_block_size);
> > > +               ALT_CMO_OP_VPA(clean, vaddr, paddr, size,
> > > riscv_cbom_block_size);
> > >                 break;
> > >         case DMA_BIDIRECTIONAL:
> > > -               ALT_CMO_OP(flush, vaddr, size,
> > > riscv_cbom_block_size);
> > > +               ALT_CMO_OP_VPA(flush, vaddr, paddr, size,
> > > riscv_cbom_block_size);
> > >                 break;
> > >         default:
> > >                 break;
> > > @@ -42,7 +42,7 @@ void arch_sync_dma_for_cpu(phys_addr_t paddr,
> > > size_t size,
> > >                 break;
> > >         case DMA_FROM_DEVICE:
> > >         case DMA_BIDIRECTIONAL:
> > > -               ALT_CMO_OP(flush, vaddr, size,
> > > riscv_cbom_block_size);
> > > +               ALT_CMO_OP_VPA(flush, vaddr, paddr, size,
> > > riscv_cbom_block_size);
> > >                 break;
> > >         default:
> > >                 break;
> > > --
> > > 2.38.1
> > >
> >
> >
>


-- 
Best Regards
 Guo Ren