From: Timur Tabi <timur@freescale.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: ucc_uart: add support for Freescale QUICCEngine UART
Date: Tue, 04 Dec 2007 16:39:57 -0600 [thread overview]
Message-ID: <4755D73D.7040204@freescale.com> (raw)
In-Reply-To: <200712042313.58252.arnd@arndb.de>
Arnd Bergmann wrote:
> I'm guessing that you don't really mean dma_addr_t here, but rather
> phys_addr_t, which is something different.
Now that I think about it, I don't know which is correct. The value is plugged
into the pointer register of a buffer descriptor, and the QE performs a DMA-like
memory transfer from that address into its local memory. I don't know if the QE
is considered "external" enough that the address is a DMA address or a physical
address.
When I program the DMA controller, I give it a dma_addr_t. And yet, the DMA
controller and the QE are both devices on the SoC. So if the DMA controller
takes a dma_addr_t, then shouldn't the QE also take one?
--
Timur Tabi
Linux kernel developer at Freescale
next prev parent reply other threads:[~2007-12-04 22:40 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-04 17:51 ucc_uart: add support for Freescale QUICCEngine UART Timur Tabi
2007-12-04 22:13 ` Arnd Bergmann
2007-12-04 22:33 ` Timur Tabi
[not found] ` <200712050037.11489.arnd@arndb.de>
2007-12-05 17:06 ` Timur Tabi
2007-12-04 22:39 ` Timur Tabi [this message]
2007-12-04 23:26 ` Arnd Bergmann
2007-12-04 23:32 ` Scott Wood
2007-12-04 23:39 ` Arnd Bergmann
2007-12-04 23:44 ` Scott Wood
2007-12-04 23:47 ` Timur Tabi
2007-12-04 23:56 ` Arnd Bergmann
2007-12-05 0:59 ` Vitaly Bordug
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=4755D73D.7040204@freescale.com \
--to=timur@freescale.com \
--cc=arnd@arndb.de \
--cc=linuxppc-dev@ozlabs.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).