From: "George Pontis" <GPontis@z9.com>
To: <linux-mtd@lists.infradead.org>
Subject: atmel_nand, DMA, and "Fall back to CPU I/O"
Date: Wed, 25 Apr 2012 15:09:14 -0700 [thread overview]
Message-ID: <037801cd2330$0cd747d0$2685d770$@com> (raw)
Working with 3.0.13 kernel and the at91sam9g45, 8b NAND flash with rootfs in
NAND
At boot, the kernel shows 22 DMA warnings, then another 260 as UBIFS mounts
the root FS:
atmel_nand atmel_nand: Fall back to CPU I/O
The Atmel nand driver is being passed an address, 0xc80000000, that fails
the test
for being at or higher than high_memory. The memory layout looks like this:
Virtual kernel memory layout:
vector : 0xffff0000 - 0xffff1000 ( 4 kB)
fixmap : 0xfff00000 - 0xfffe0000 ( 896 kB)
DMA : 0xffa00000 - 0xffe00000 ( 4 MB)
vmalloc : 0xc8800000 - 0xfee00000 ( 870 MB)
lowmem : 0xc0000000 - 0xc8000000 ( 128 MB)
modules : 0xbf000000 - 0xc0000000 ( 16 MB)
.init : 0xc0008000 - 0xc0027000 ( 124 kB)
.text : 0xc0027000 - 0xc0456d8c (4288 kB)
.data : 0xc0458000 - 0xc0480ae0 ( 163 kB)
.bss : 0xc0480b04 - 0xc04ab8b4 ( 172 kB)
Is it normal for a driver to get an address that is not inside one of these
ranges, whether
it used vmalloc or not ?
If the driver is not going to get pointers to a DMA-safe area, would it not
be better
to disable DMA, or at least set the default use_dma=0 ?
George
next reply other threads:[~2012-04-25 22:09 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-25 22:09 George Pontis [this message]
2012-05-02 11:53 ` atmel_nand, DMA, and "Fall back to CPU I/O" Artem Bityutskiy
2012-05-02 19:32 ` Brian Norris
2012-05-03 10:35 ` Artem Bityutskiy
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='037801cd2330$0cd747d0$2685d770$@com' \
--to=gpontis@z9.com \
--cc=linux-mtd@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 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.