From: Guo Ren <guoren@kernel.org>
To: Anup Patel <anup@brainfault.org>
Cc: "Drew Fustini" <drew@beagleboard.org>,
"Christoph Hellwig" <hch@lst.de>,
"Anup Patel" <anup.patel@wdc.com>,
"Palmer Dabbelt" <palmerdabbelt@google.com>,
wefu@redhat.com, "Wei Wu (吴伟)" <lazyparser@gmail.com>,
linux-riscv <linux-riscv@lists.infradead.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
linux-sunxi@lists.linux.dev, "Guo Ren" <guoren@linux.alibaba.com>,
"Paul Walmsley" <paul.walmsley@sifive.com>
Subject: Re: [PATCH RFC 0/3] riscv: Add DMA_COHERENT support
Date: Thu, 20 May 2021 09:59:04 +0800 [thread overview]
Message-ID: <CAJF2gTR2gWETwiszV0n4otjHxu0hGXDp1TT9n=8hX8UHVZY3tw@mail.gmail.com> (raw)
In-Reply-To: <CAJF2gTQKqce_6cmGQnfLOX8uXvOUWUR-pQT4yOMioMcFAPfBjQ@mail.gmail.com>
On Thu, May 20, 2021 at 9:47 AM Guo Ren <guoren@kernel.org> wrote:
>
> On Wed, May 19, 2021 at 3:15 PM Anup Patel <anup@brainfault.org> wrote:
> >
> > On Wed, May 19, 2021 at 12:24 PM Drew Fustini <drew@beagleboard.org> wrote:
> > >
> > > On Wed, May 19, 2021 at 08:06:17AM +0200, Christoph Hellwig wrote:
> > > > On Wed, May 19, 2021 at 02:05:00PM +0800, Guo Ren wrote:
> > > > > Since the existing RISC-V ISA cannot solve this problem, it is better
> > > > > to provide some configuration for the SOC vendor to customize.
> > > >
> > > > We've been talking about this problem for close to five years. So no,
> > > > if you don't manage to get the feature into the ISA it can't be
> > > > supported.
> > >
> > > Isn't it a good goal for Linux to support the capabilities present in
> > > the SoC that a currently being fab'd?
> > >
> > > I believe the CMO group only started last year [1] so the RV64GC SoCs
> > > that are going into mass production this year would not have had the
> > > opporuntiy of utilizing any RISC-V ISA extension for handling cache
> > > management.
> >
> > The current Linux RISC-V policy is to only accept patches for frozen or
> > ratified ISA specs.
> > (Refer, Documentation/riscv/patch-acceptance.rst)
> >
> > This means even if emulate CMO instructions in OpenSBI, the Linux
I think it's CBO now.
https://github.com/riscv/riscv-CMOs/blob/master/discussion-files/RISC_V_range_CMOs_bad_v1.00.pdf
> > patches won't be taken by Palmer because CMO specification is
> > still in draft stage.
> How do you think about
> sbi_ecall(SBI_EXT_DMA, SBI_DMA_SYNC, start, size, dir, 0, 0, 0);
> ? thx
CBO insn trap is okay for me ;-)
> >
> > Also, we all know how much time it takes for RISCV international
> > to freeze some spec. Judging by that we are looking at another
> > 3-4 years at minimum.
> >
> > Regards,
> > Anup
>
>
>
> --
> Best Regards
> Guo Ren
>
> ML: https://lore.kernel.org/linux-csky/
--
Best Regards
Guo Ren
ML: https://lore.kernel.org/linux-csky/
next prev parent reply other threads:[~2021-05-20 1:59 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-19 5:04 [PATCH RFC 0/3] riscv: Add DMA_COHERENT support guoren
2021-05-19 5:04 ` [PATCH RFC 1/3] riscv: pgtable.h: Fixup _PAGE_CHG_MASK usage guoren
2021-05-19 5:04 ` [PATCH RFC 2/3] riscv: Add DMA_COHERENT for custom PTE attributes guoren
2021-05-19 5:04 ` [PATCH RFC 3/3] riscv: Add SYNC_DMA_FOR_CPU/DEVICE for DMA_COHERENT guoren
2021-05-19 6:32 ` Guo Ren
2021-05-19 5:20 ` [PATCH RFC 0/3] riscv: Add DMA_COHERENT support Christoph Hellwig
2021-05-19 5:48 ` Guo Ren
2021-05-19 5:55 ` Christoph Hellwig
2021-05-19 6:09 ` Guo Ren
2021-05-19 6:44 ` Drew Fustini
2021-05-19 6:53 ` Christoph Hellwig
2021-05-20 1:45 ` Guo Ren
2021-05-20 5:48 ` Christoph Hellwig
2021-06-06 18:14 ` Nick Kossifidis
2021-06-07 0:04 ` Guo Ren
2021-06-07 2:16 ` Nick Kossifidis
2021-06-07 3:19 ` Guo Ren
2021-06-07 6:27 ` Christoph Hellwig
2021-06-07 6:41 ` Guo Ren
2021-06-07 6:51 ` Christoph Hellwig
2021-06-07 7:46 ` Guo Ren
2021-06-08 15:00 ` David Laight
2021-06-08 15:32 ` 'Christoph Hellwig'
2021-06-08 16:11 ` David Laight
2021-06-07 8:35 ` Nick Kossifidis
2021-06-09 3:28 ` Guo Ren
2021-06-09 6:05 ` Jisheng Zhang
2021-06-09 9:45 ` Nick Kossifidis
2021-06-09 12:43 ` Guo Ren
2021-05-19 6:05 ` Guo Ren
2021-05-19 6:06 ` Christoph Hellwig
2021-05-19 6:11 ` Guo Ren
2021-05-19 6:54 ` Drew Fustini
2021-05-19 6:56 ` Christoph Hellwig
2021-05-19 7:14 ` Anup Patel
2021-05-19 8:25 ` Damien Le Moal
2021-05-20 1:47 ` Guo Ren
2021-05-20 1:59 ` Guo Ren [this message]
2021-05-22 0:36 ` Guo Ren
2021-05-30 0:30 ` Palmer Dabbelt
2021-06-03 4:13 ` Palmer Dabbelt
2021-06-03 6:00 ` Anup Patel
2021-06-03 15:39 ` Palmer Dabbelt
2021-06-04 9:02 ` David Laight
2021-06-04 9:53 ` Arnd Bergmann
2021-06-04 14:47 ` Guo Ren
2021-06-04 16:12 ` Palmer Dabbelt
2021-06-04 21:26 ` Arnd Bergmann
2021-06-04 22:10 ` Palmer Dabbelt
2021-06-08 12:26 ` Guo Ren
2021-06-06 17:11 ` Guo Ren
2021-06-07 3:38 ` Anup Patel
2021-06-07 4:22 ` Guo Ren
2021-06-07 4:47 ` Anup Patel
2021-06-07 5:08 ` Guo Ren
2021-06-07 5:13 ` Guo Ren
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAJF2gTR2gWETwiszV0n4otjHxu0hGXDp1TT9n=8hX8UHVZY3tw@mail.gmail.com' \
--to=guoren@kernel.org \
--cc=anup.patel@wdc.com \
--cc=anup@brainfault.org \
--cc=drew@beagleboard.org \
--cc=guoren@linux.alibaba.com \
--cc=hch@lst.de \
--cc=lazyparser@gmail.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=linux-sunxi@lists.linux.dev \
--cc=palmerdabbelt@google.com \
--cc=paul.walmsley@sifive.com \
--cc=wefu@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).