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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

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