All of lore.kernel.org
 help / color / mirror / Atom feed
From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
	Rob Herring <robh@kernel.org>,
	ALSA Development Mailing List <alsa-devel@alsa-project.org>,
	Mark Brown <broonie@kernel.org>,
	Liam Girdwood <lgirdwood@gmail.com>,
	Vinod Koul <vinod.koul@intel.com>,
	dmaengine@vger.kernel.org, Joerg Roedel <joro@8bytes.org>,
	Linux IOMMU <iommu@lists.linux-foundation.org>,
	Magnus Damm <magnus.damm@gmail.com>
Subject: Re: of_dma_request_slave_channel() failed ?
Date: Fri, 14 Sep 2018 08:56:31 +0200	[thread overview]
Message-ID: <CAMuHMdWHGE0R_qeKCstcCiSc6YYC8GAqX1ZcsyafWP=DmTJgLA@mail.gmail.com> (raw)
In-Reply-To: <87lg84ucrr.wl-kuninori.morimoto.gx@renesas.com>

Hi Morimoto-san,

On Fri, Sep 14, 2018 at 2:53 AM Kuninori Morimoto
<kuninori.morimoto.gx@renesas.com> wrote:
> > > Before 6c92d5a2744e2761 patch, driver will forcibly ignore
> > > non-SSI modules, and try to use PIO mode.
> > > I'm not sure it is "kindly support" or "overkill support".
> > >
> > > After this patch, it needs DMA, otherwise, probe will be failed.
> > > DT shouldn't have non-SSI modules if you want to use PIO mode.
> > >
> > >         + /* use PIO mode */
> > >         - playback = <&ssi0 &src0 &dvc0>;
> > >         + playback = <&ssi0>;
> >
> > OK, so falling back to PIO was really a "best effort" fallback, and the user
> > should really enable DMA?
>
> Yeah, I'm thinking this is better.
> PIO fallback is of course "nice to have" if possible.
> But, because of this new iommu patch, keeping this feature
> needs "big complicated patch", and we can get "small effect" I think.
> Thus, I think this is the time to remove this feature.
> Can you agree ?

You're the rcar-sound expert ;-)
If you think there's not much value in keeping PIO fallback, it can be
removed.

We can change behavior once these dependency issues have been resolved
in a generic way.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

WARNING: multiple messages have this Message-ID (diff)
From: Geert Uytterhoeven <geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org>
To: Kuninori Morimoto
	<kuninori.morimoto.gx-zM6kxYcvzFBBDgjK7y7TUQ@public.gmane.org>
Cc: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	ALSA Development Mailing List
	<alsa-devel-K7yf7f+aM1XWsZ/bQMPhNw@public.gmane.org>,
	Vinod Koul <vinod.koul-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	Magnus Damm <magnus.damm-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Liam Girdwood <lgirdwood-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Linux-Renesas
	<linux-renesas-soc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Linux IOMMU
	<iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>,
	Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	dmaengine-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: of_dma_request_slave_channel() failed ?
Date: Fri, 14 Sep 2018 08:56:31 +0200	[thread overview]
Message-ID: <CAMuHMdWHGE0R_qeKCstcCiSc6YYC8GAqX1ZcsyafWP=DmTJgLA@mail.gmail.com> (raw)
In-Reply-To: <87lg84ucrr.wl-kuninori.morimoto.gx-zM6kxYcvzFBBDgjK7y7TUQ@public.gmane.org>

Hi Morimoto-san,

On Fri, Sep 14, 2018 at 2:53 AM Kuninori Morimoto
<kuninori.morimoto.gx-zM6kxYcvzFBBDgjK7y7TUQ@public.gmane.org> wrote:
> > > Before 6c92d5a2744e2761 patch, driver will forcibly ignore
> > > non-SSI modules, and try to use PIO mode.
> > > I'm not sure it is "kindly support" or "overkill support".
> > >
> > > After this patch, it needs DMA, otherwise, probe will be failed.
> > > DT shouldn't have non-SSI modules if you want to use PIO mode.
> > >
> > >         + /* use PIO mode */
> > >         - playback = <&ssi0 &src0 &dvc0>;
> > >         + playback = <&ssi0>;
> >
> > OK, so falling back to PIO was really a "best effort" fallback, and the user
> > should really enable DMA?
>
> Yeah, I'm thinking this is better.
> PIO fallback is of course "nice to have" if possible.
> But, because of this new iommu patch, keeping this feature
> needs "big complicated patch", and we can get "small effect" I think.
> Thus, I think this is the time to remove this feature.
> Can you agree ?

You're the rcar-sound expert ;-)
If you think there's not much value in keeping PIO fallback, it can be
removed.

We can change behavior once these dependency issues have been resolved
in a generic way.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

  reply	other threads:[~2018-09-14 12:09 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-04  6:06 of_dma_request_slave_channel() failed ? Kuninori Morimoto
2018-09-11  9:43 ` Geert Uytterhoeven
2018-09-11  9:43   ` Geert Uytterhoeven
2018-09-12 15:50   ` Mark Brown
2018-09-12 15:50     ` Mark Brown
2018-09-13  9:00     ` Geert Uytterhoeven
2018-09-13  9:00       ` Geert Uytterhoeven
2018-09-13 10:11       ` Robin Murphy
2018-09-13 10:11         ` Robin Murphy
2018-09-13 11:04         ` Geert Uytterhoeven
2018-09-13 11:04           ` Geert Uytterhoeven
2018-09-14  1:10           ` Kuninori Morimoto
2018-09-14  1:10             ` Kuninori Morimoto
2018-09-13  5:48   ` Kuninori Morimoto
2018-09-13  5:48     ` Kuninori Morimoto
2018-09-13  8:38     ` Geert Uytterhoeven
2018-09-13  8:38       ` Geert Uytterhoeven
2018-09-14  0:53       ` Kuninori Morimoto
2018-09-14  0:53         ` Kuninori Morimoto
2018-09-14  6:56         ` Geert Uytterhoeven [this message]
2018-09-14  6:56           ` Geert Uytterhoeven

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='CAMuHMdWHGE0R_qeKCstcCiSc6YYC8GAqX1ZcsyafWP=DmTJgLA@mail.gmail.com' \
    --to=geert@linux-m68k.org \
    --cc=alsa-devel@alsa-project.org \
    --cc=broonie@kernel.org \
    --cc=dmaengine@vger.kernel.org \
    --cc=iommu@lists.linux-foundation.org \
    --cc=joro@8bytes.org \
    --cc=kuninori.morimoto.gx@renesas.com \
    --cc=lgirdwood@gmail.com \
    --cc=linux-renesas-soc@vger.kernel.org \
    --cc=magnus.damm@gmail.com \
    --cc=robh@kernel.org \
    --cc=vinod.koul@intel.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.