Re: [PATCH V2 2/6] of/slimbus: OF helper for SLIMbus

From: Sagar Dharia <sdharia@codeaurora.org>
To: Mark Brown <broonie@kernel.org>
Cc: gregkh@linuxfoundation.org, bp@suse.de, poeschel@lemonage.de,
	treding@nvidia.com, gong.chen@linux.intel.com,
	andreas.noever@gmail.com, alan@linux.intel.com,
	mathieu.poirier@linaro.org, daniel@ffwll.ch, oded.gabbay@amd.com,
	jkosina@suse.cz, sharon.dvir1@mail.huji.ac.il, joe@perches.com,
	davem@davemloft.net, james.hogan@imgtec.com,
	michael.opdenacker@free-electrons.com,
	daniel.thompson@linaro.org, linux-kernel@vger.kernel.org,
	nkaje@codeaurora.org, kheitke@audience.com,
	mlocke@codeaurora.org, agross@codeaurora.org,
	linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH V2 2/6] of/slimbus: OF helper for SLIMbus
Date: Wed, 17 Jun 2015 11:01:42 -0600	[thread overview]
Message-ID: <5581A7F6.5060902@codeaurora.org> (raw)
In-Reply-To: <20150617130932.GF3214@sirena.org.uk>

On 6/17/2015 7:09 AM, Mark Brown wrote:
> On Tue, Jun 16, 2015 at 07:46:00PM -0600, Sagar Dharia wrote:
>> OF helper routine scans the SLIMbus DeviceTree, allocates resources,
>> and creates slim_devices according to the hierarchy.
> You've not CCed any of the DT maintainers on this, for a completely new
> bus it seems like we really ought to get their input.
Will do.
>
>> @@ -0,0 +1,34 @@
>> +SLIM(Serial Low Power Interchip Media Bus) bus
>> +
>> +SLIMbus is a 2-wire bus, and is used to communicate with peripheral
>> +components like audio-codec.
>> +
>> +Required property for SLIMbus controller node:
>> +- compatible	- name of SLIMbus controller.
>> +
>> +No other properties are required in the SLIMbus controller bus node.
> It seems better to just say that the controller is a normal device using
> the binding for whatever bus it is on and that the binding is for the
> bus which is a child node of the controller device?  Also, do we need
> #address-cells or #size-cells here?
It will be required if we use 'reg' property for enumeration address per 
my understanding (address-cells: 6, size-cells: 0)
I thought about using 'reg' and it seemed to work as well. Only reason 
for using 'enumeration-addr' was to be closer to what HW calls it.
Looking at other device-trees, (that 'reg' was used for other buses to 
represent slave address), I will document the 'reg' property and 
document it.
Thanks
Sagar
>
>> +Required property for SLIMbus child node:
>> +enumeration-addr	- 6 byte enumeration address of the slave
> The idiom for DT seems to be that we define the bus address using the
> reg property.  Should we not be following that pattern here too?  I'd
> also expect to see the ability to define a compatible for the slaves.


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