All of lore.kernel.org
 help / color / mirror / Atom feed
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

  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 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.