LinuxPPC-Dev Archive on lore.kernel.org
 help / color / Atom feed
From: Christoph Hellwig <hch@lst.de>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, hch@lst.de,
	linux-kernel@vger.kernel.org,
	Rui Salvaterra <rsalvaterra@gmail.com>
Subject: Re: use generic DMA mapping code in powerpc V4
Date: Sat, 8 Dec 2018 18:17:46 +0100
Message-ID: <20181208171746.GB15228@lst.de> (raw)
In-Reply-To: <42b1408cafe77ebac1b1ad909db237fe34e4d177.camel@kernel.crashing.org>

On Sun, Dec 02, 2018 at 05:11:02PM +1100, Benjamin Herrenschmidt wrote:
> Talking of which ... Christoph, not sure if we can do something about
> this at the DMA API level or keep hacks but some adapters such as the
> nVidia GPUs have a HW hack we can use to work around their limitations
> in that case.
> 
> They have a register that can program a fixed value for the top bits
> that they don't support.
> 
> This works fine for any linear mapping with an offset, provided they
> can program the offset in that register and they have enough DMA range
> to cover all memory from that offset.
> 
> I can probably get the info about this from them so we can exploit it
> in nouveau.

I think we can expose the direct mapping offset if people care enough,
we just have to be very careful designing the API.  I'll happily leave
that to those that actually want to use it, but I'll gladly help
reviewing it.

  reply index

Thread overview: 127+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-29 19:45 Rui Salvaterra
2018-11-30 10:32 ` Christoph Hellwig
2018-11-30 11:44   ` Rui Salvaterra
2018-11-30 16:41     ` Rui Salvaterra
2018-12-02  6:11     ` Benjamin Herrenschmidt
2018-12-08 17:17       ` Christoph Hellwig [this message]
2018-12-10 17:04         ` Rui Salvaterra
2018-12-10 19:33           ` Christoph Hellwig
2018-12-10 20:03             ` Rui Salvaterra
2018-12-10 20:49             ` Benjamin Herrenschmidt
2018-12-11  9:37               ` Rui Salvaterra
  -- strict thread matches above, loose matches on Subject: below --
2018-11-14  8:22 Christoph Hellwig
2018-11-27  7:42 ` Christoph Hellwig
2018-11-27 22:05   ` Benjamin Herrenschmidt
2018-11-28 11:05   ` Michael Ellerman
2018-11-28 15:55     ` Christian Zigotzky
2018-11-28 20:02       ` Christian Zigotzky
2018-11-28 20:35       ` Michal Suchánek
2018-11-29 17:03         ` Christoph Hellwig
2019-12-19 13:54       ` Christian Zigotzky
2018-11-29 12:05     ` Christian Zigotzky
2018-11-29 15:30       ` Christian Zigotzky
2018-11-29 17:03       ` Christoph Hellwig
2018-11-29 23:07         ` Christian Zigotzky
2018-11-30 10:53           ` Christoph Hellwig
2018-11-30 12:23             ` Christian Zigotzky
2018-11-30 13:10               ` Christoph Hellwig
2018-11-30 15:29                 ` Christian Zigotzky
2018-12-04  7:31                   ` Christian Zigotzky
2018-12-04  9:53                     ` Christian Zigotzky
2018-12-04 14:24                       ` Christoph Hellwig
2018-12-05  9:44                         ` Christian Zigotzky
2018-12-05 14:05                           ` Christoph Hellwig
2018-12-06 10:55                             ` Christian Zigotzky
2018-12-06 17:10                               ` Christian Zigotzky
2018-12-06 19:36                                 ` Christoph Hellwig
2018-12-07  7:48                                   ` Christian Zigotzky
2018-12-07 13:45                               ` Christian Zigotzky
2018-12-07 18:33                                 ` Christian Zigotzky
2018-12-08 10:29                                   ` Christian Zigotzky
2018-12-08 13:47                                     ` Christian Zigotzky
2018-12-09 14:20                                       ` Christian Zigotzky
2018-12-09 18:26                                         ` Christian Zigotzky
2018-12-10 15:54                                           ` Christian Zigotzky
2018-12-11 14:28                                             ` Christian Zigotzky
2018-12-11 18:17                                               ` Christian Zigotzky
2018-12-12  0:47                                                 ` Benjamin Herrenschmidt
2018-12-12  7:03                                                   ` Christian Zigotzky
2018-12-12 14:15                                                 ` Christoph Hellwig
2018-12-12 14:39                                                   ` Christian Zigotzky
2018-12-13  8:41                                                     ` Christian Zigotzky
2018-12-13  9:10                                                       ` Christoph Hellwig
2018-12-13  9:47                                                         ` Christian Zigotzky
2018-12-13 11:19                                                           ` Christian Zigotzky
2018-12-13 11:25                                                             ` Christoph Hellwig
2018-12-13 13:34                                                               ` Christian Zigotzky
2018-12-13 17:48                                                                 ` Christian Zigotzky
2018-12-13 21:53                                                                   ` Christian Zigotzky
2018-12-14 12:00                                                                     ` Christian Zigotzky
2018-12-14 16:45                                                                       ` Christoph Hellwig
2019-01-03  7:36                                                                       ` Christoph Hellwig
2019-01-03 19:26                                                                         ` Christian Zigotzky
2019-01-05 16:03                                                                           ` Christian Zigotzky
2019-01-09  9:31                                                                             ` Christian Zigotzky
2019-01-11  2:10                                                                               ` Christian Zigotzky
2019-01-12 18:14                                                                                 ` Christian Zigotzky
2019-01-15  8:07                                                                                   ` Christian Zigotzky
2019-01-15  8:49                                                                                     ` Christian Zigotzky
2019-01-15 10:55                                                                                       ` Christian Zigotzky
2019-01-15 13:35                                                                                         ` Christoph Hellwig
2019-01-15 13:56                                                                                           ` Christian Zigotzky
2019-01-15 15:17                                                                                             ` Christoph Hellwig
2019-01-17  9:21                                                                                               ` Christian Zigotzky
2019-01-17  9:31                                                                                                 ` Christoph Hellwig
2019-01-17  9:44                                                                                                   ` Christian Zigotzky
2019-01-18  8:35                                                                                                 ` Christoph Hellwig
2019-01-18 11:10                                                                                                   ` Christian Zigotzky
2019-01-18 11:28                                                                                                     ` Christoph Hellwig
2019-01-18 12:07                                                                                                       ` Christian Zigotzky
2019-01-18 12:18                                                                                                         ` Christoph Hellwig
2019-01-18 12:46                                                                                                           ` Christian Zigotzky
2019-01-18 12:55                                                                                                             ` Christoph Hellwig
2019-01-18 15:06                                                                                                               ` Christian Zigotzky
2019-01-19 11:40                                                                                                                 ` Christian Zigotzky
2019-01-19 11:52                                                                                                                   ` Christian Zigotzky
2019-01-19 13:02                                                                                                                     ` Christoph Hellwig
2019-01-19 14:04                                                                                                                       ` Christoph Hellwig
2019-01-21 14:38                                                                                                                         ` Christian Zigotzky
2019-01-23 14:34                                                                                                                           ` Christian Zigotzky
2019-01-25 13:37                                                                                                                             ` Christian Zigotzky
2019-01-27 13:13                                                                                                                               ` Christian Zigotzky
2019-01-28  7:04                                                                                                                                 ` Christoph Hellwig
2019-01-28 16:22                                                                                                                                   ` Christoph Hellwig
2019-01-28 16:52                                                                                                                                     ` Christian Zigotzky
2019-01-29 15:03                                                                                                                                       ` Christian Zigotzky
2019-01-29 16:14                                                                                                                                         ` Christoph Hellwig
2019-01-29 16:34                                                                                                                                           ` Christoph Hellwig
2019-01-30  4:40                                                                                                                                             ` Christian Zigotzky
2019-01-31 12:48                                                                                                                                               ` Christian Zigotzky
2019-02-01  8:04                                                                                                                                                 ` Christoph Hellwig
2019-02-01 16:54                                                                                                                                                   ` Christian Zigotzky
2019-02-03 16:49                                                                                                                                                     ` Christian Zigotzky
2019-02-04  7:56                                                                                                                                                       ` Christoph Hellwig
2019-02-04 12:13                                                                                                                                                         ` Christian Zigotzky
2019-02-04 12:38                                                                                                                                                           ` Christoph Hellwig
2019-02-06 13:45                                                                                                                                                             ` Christian Zigotzky
2019-02-06 15:15                                                                                                                                                               ` Christoph Hellwig
2019-02-06 15:16                                                                                                                                                                 ` Christoph Hellwig
2019-02-07  4:34                                                                                                                                                                   ` Christian Zigotzky
2019-02-08  9:01                                                                                                                                                                     ` Christian Zigotzky
2019-02-08  9:18                                                                                                                                                                       ` Christoph Hellwig
2019-02-08 10:59                                                                                                                                                                         ` Christian Zigotzky
2019-02-09 19:26                                                                                                                                                                         ` Darren Stevens
2019-02-09 21:10                                                                                                                                                                         ` Darren Stevens
2019-02-11  7:41                                                                                                                                                                           ` Christoph Hellwig
2019-02-10 12:00                                                                                                                                                                         ` Christian Zigotzky
     [not found]                                                                                                                                                                           ` <0042290A-2939-4EBA-A638-D404FA2055ED@xenosoft.de>
2019-02-11  7:21                                                                                                                                                                             ` Christian Zigotzky
2019-02-11  7:38                                                                                                                                                                           ` Christoph Hellwig
2019-02-12 12:42                                                                                                                                                                             ` Christian Zigotzky
2019-02-12 15:25                                                                                                                                                                               ` Christoph Hellwig
2019-02-12 19:31                                                                                                                                                                                 ` Christian Zigotzky
2019-02-12 19:50                                                                                                                                                                                   ` Christian Zigotzky
2019-02-12 19:52                                                                                                                                                                                     ` Christoph Hellwig
2018-11-29 17:02     ` Christoph Hellwig
2018-12-08 17:03 ` Christoph Hellwig
2018-12-16 16:51 ` Christoph Hellwig
2018-12-17  1:14   ` Michael Ellerman

Reply instructions:

You may reply publically 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=20181208171746.GB15228@lst.de \
    --to=hch@lst.de \
    --cc=benh@kernel.crashing.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=rsalvaterra@gmail.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

LinuxPPC-Dev Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linuxppc-dev/0 linuxppc-dev/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linuxppc-dev linuxppc-dev/ https://lore.kernel.org/linuxppc-dev \
		linuxppc-dev@lists.ozlabs.org linuxppc-dev@ozlabs.org
	public-inbox-index linuxppc-dev

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.ozlabs.lists.linuxppc-dev


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git