linux-kernel - Re: [PATCH v4 3/4] dt-bindings: phy: Add support for QMP phy

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Date:   Thu, 19 Jan 2017 10:42:05 +0530
From:   Vivek Gautam <vivek.gautam@...eaurora.org>
To:     Stephen Boyd <sboyd@...eaurora.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Kishon Vijay Abraham I <kishon@...com>, robh+dt@...nel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        mark.rutland@....com, srinivas.kandagatla@...aro.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v4 3/4] dt-bindings: phy: Add support for QMP phy


On 01/19/2017 06:10 AM, Stephen Boyd wrote:
> On 01/18, Bjorn Andersson wrote:
>> On Tue 17 Jan 22:54 PST 2017, Vivek Gautam wrote:
>>> On 01/16/2017 02:19 PM, Kishon Vijay Abraham I wrote:
>>>> On Tuesday 10 January 2017 04:21 PM, Vivek Gautam wrote:
>> [..]
>>>>> +		reset-names = "phy", "common", "cfg",
>>>>> +				"lane0", "lane1", "lane2";
>>>> Each lane has a separate clock, separate reset.. why not create sub-nodes for
>>>> each lane?
>>> Yes, each lane has separate pipe clock and resets.
>>> I can have a binding such as written below.
>> +1
>>
>>> Does it makes sense to pull in the tx, rx and pcs offsets as well
>>> to the child node, and iomap the entire address space of the phy ?
>>>
>> Note that you don't have to follow the same structure in your device
>> driver as you describe your hardware in devicetree.
>>
>> I would suggest that you replace the lane-offset and various lane
>> specific resources with subnodes, but keep the driver "as is".
>>
> Didn't we already move away from subnodes for lanes in an earlier
> revision of these patches? I seem to recall we did that because
> lanes are not devices and the whole "phy as a bus" concept not
> making sense.

Yea, we started out without having any sub-nodes and we
argued that we don't require them since the qmp device is
represented by the qmp node itself.
The lanes otoh are representative of gen_phys and related properties.

In the driver -
"struct qmp_phy " represents the lanes and holds "struct phy",
"struct qcom_qmp" represents the qmp block as a whole and holds "struct 
device"
Does this make lanes qualify to be childs of qmp ?

"phy as a bus" (just trying to understand here) -
let's say a usb phy controller has one HSIC phy port and one USB2 phy port.
So, should this phy controller be a bus providing two ports (and so we 
will have
couple of child nodes to the phy controller) ?


Regards
Vivek

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