From: Christoph Hellwig <hch@lst.de>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rui Salvaterra <rsalvaterra@gmail.com>,
hch@lst.de, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org,
linux-kernel@vger.kernel.org
Subject: Re: use generic DMA mapping code in powerpc V4
Date: Sat, 8 Dec 2018 18:17:46 +0100 [thread overview]
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.
next prev parent reply other threads:[~2018-12-08 17:17 UTC|newest]
Thread overview: 125+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-29 19:45 use generic DMA mapping code in powerpc V4 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
2019-02-10 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
2018-11-30 3:17 ` Benjamin Herrenschmidt
2018-12-08 17:03 ` Christoph Hellwig
2018-12-16 16:51 ` Christoph Hellwig
2018-12-17 1:14 ` Michael Ellerman
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