From: magnus.damm@gmail.com (Magnus Damm)
To: linux-arm-kernel@lists.infradead.org
Subject: CONSISTENT_DMA_SIZE limitations
Date: Wed, 28 Apr 2010 15:25:41 +0900 [thread overview]
Message-ID: <v2taec7e5c31004272325x9e5958ddp34d7db1ff3477f4d@mail.gmail.com> (raw)
Hi everyone,
Are there any special CONSISTENT_DMA_SIZE limitiations in the latest
upstrem ARM kernel?
On SH-Mobile ARM a single 256 MB I/O window is mapped virt:phys 1:1 at
0xe6000000 -> 0xf5ffffff at ->map_io() time.
The virtual area on top of the I/O window at 0xf6000000 -> 0xffdfffff
seems suitable for consistent dma mappings. Extending
CONSISTENT_DMA_SIZE from the default 2MB to 158 MB makes efficient use
of the entire range. Empty 2MB space is left at the top as usual.
Extending CONSISTENT_DMA_SIZE seems like a good idea to me, but I'm
not sure if doing so will break something else. Perhaps I need to
rework some code in arch/arm/mm/dma-mapping.c?
I'm asking because most platforms only export up to 14 MB, and
Documentation/arm/memory.txt mentions 0xff000000 -> 0xffbfffff as
reserved.
Thanks!
/ magnus
next reply other threads:[~2010-04-28 6:25 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-28 6:25 Magnus Damm [this message]
2010-04-28 6:47 ` CONSISTENT_DMA_SIZE limitations Eric Miao
2010-04-28 7:07 ` Shilimkar, Santosh
2010-04-28 7:53 ` Magnus Damm
2010-04-28 7:08 ` Magnus Damm
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=v2taec7e5c31004272325x9e5958ddp34d7db1ff3477f4d@mail.gmail.com \
--to=magnus.damm@gmail.com \
--cc=linux-arm-kernel@lists.infradead.org \
/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).