From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <galak@kernel.crashing.org>
Received: from gate.crashing.org (gate.crashing.org [63.228.1.57])
	(using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits))
	(Client did not present a certificate)
	by ozlabs.org (Postfix) with ESMTPS id 5BCF8DDF5C
	for <linuxppc-dev@ozlabs.org>; Tue,  1 Jul 2008 01:38:15 +1000 (EST)
Message-Id: <D70C5CB6-5066-4AD3-9367-879AF39FB8E1@kernel.crashing.org>
From: Kumar Gala <galak@kernel.crashing.org>
To: Scott Wood <scottwood@freescale.com>
In-Reply-To: <20080630153513.GD13950@loki.buserror.net>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
Mime-Version: 1.0 (Apple Message framework v924)
Subject: Re: [PATCH v2] powerpc: Add dma nodes to 83xx, 85xx and 86xx boards
Date: Mon, 30 Jun 2008 10:38:03 -0500
References: <Pine.LNX.4.64.0806271449540.9071@blarg.am.freescale.net>
	<48654D6D.1090309@freescale.com>
	<E57F448A-7217-4893-A77B-6367B0C3118A@kernel.crashing.org>
	<Pine.LNX.4.64.0806271609540.10625@blarg.am.freescale.net>
	<20080630041525.GD24012@yookeroo.seuss>
	<20080630153513.GD13950@loki.buserror.net>
Cc: "linuxppc-dev@ozlabs.org list" <linuxppc-dev@ozlabs.org>,
	Timur Tabi <timur@freescale.com>
List-Id: Linux on PowerPC Developers Mail List <linuxppc-dev.ozlabs.org>
List-Unsubscribe: <https://ozlabs.org/mailman/options/linuxppc-dev>,
	<mailto:linuxppc-dev-request@ozlabs.org?subject=unsubscribe>
List-Archive: <http://ozlabs.org/pipermail/linuxppc-dev>
List-Post: <mailto:linuxppc-dev@ozlabs.org>
List-Help: <mailto:linuxppc-dev-request@ozlabs.org?subject=help>
List-Subscribe: <https://ozlabs.org/mailman/listinfo/linuxppc-dev>,
	<mailto:linuxppc-dev-request@ozlabs.org?subject=subscribe>


On Jun 30, 2008, at 10:35 AM, Scott Wood wrote:

> On Mon, Jun 30, 2008 at 02:15:25PM +1000, David Gibson wrote:
>> On Fri, Jun 27, 2008 at 04:10:17PM -0500, Kumar Gala wrote:
>>> Added DMA nodes for the elo/elo-plus DMA engines.
>>>
>>> Renamed the interrupt controller alias in mpc832x_rdb.dts to ipic  
>>> so that
>>> its the same as all the other boards.
>>>
>>> Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
>>
>> [snip]
>>> diff --git a/arch/powerpc/boot/dts/asp834x-redboot.dts b/arch/ 
>>> powerpc/boot/dts/asp834x-redboot.dts
>>> index 972cf78..8b1bb0e 100644
>>> --- a/arch/powerpc/boot/dts/asp834x-redboot.dts
>>> +++ b/arch/powerpc/boot/dts/asp834x-redboot.dts
>>> @@ -118,6 +118,41 @@
>>> 			mode = "cpu";
>>> 		};
>>>
>>> +		dma@82a8 {
>>> +			#address-cells = <1>;
>>> +			#size-cells = <1>;
>>> +			compatible = "fsl,mpc8347-dma", "fsl,elo-dma";
>>> +			reg = <0x82a8 4>;
>>> +			ranges = <0 0x8100 0x1a8>;
>>> +			interrupt-parent = <&ipic>;
>>> +			interrupts = <71 8>;
>>> +			cell-index = <0>;
>>
>> What's the cell-index in these nodes used to index?  Given the
>> confusion there's been about the proper use of this property, a
>> comment indicating which shared registers this is used to index is
>> probably a good idea.
>
> There's supposed to be a cell-index in the *channels* to index into  
> the
> shared summary register (the "reg" of the dma node itself).  I don't  
> see any
> purpose for a cell-index in the main dma node, though.

I believe this comes into play when we have more than one DMA  
controller and sometimes there are special uses like on 8610.

- k