Re: [RFC PATCH 4/5] arm: omap2: support port power on lan95xx devices

[Andy Green <andy.green@linaro.org>]

On 05/12/12 02:14, the mail apparently from Sarah Sharp included:
> On Tue, Dec 04, 2012 at 11:40:05AM +0800, Andy Green wrote:
>> On 04/12/12 01:09, the mail apparently from Alan Stern included:
>>> On Mon, 3 Dec 2012, Andy Green wrote:
>>>
>>>> Unless someone NAKs it for sure already (if you're already sure you're
>>>> going to, please do so to avoid wasting time), I'll issue a try#2 of my
>>>> code later which demonstrates what I mean.  At least I guess it's useful
>>>> for comparative purposes.
>>>
>>> Before you go writing a whole lot more code, we should discuss the
>>> basics a bit more clearly.  There are several unsettled issues here:
>>
>>>       1. Should the LAN95xx stuff be associated with the ehci-omap.0's
>>> 	driver or with the hub port?  The port would be more flexible,
>>> 	offering the ability to turn the power off and on while the
>>> 	system is running without affecting anything else.  But the
>>> 	port code is currently in flux, which could cause this new
>>> 	addition to be delayed.
>>
>> I think associating ULPI PHY reset and SMSC power and reset with the
>> hub port power state is good.  Then, you could have the driver in a
>> device with multiple onboard USB devices, and individually control
>> whether they're eating power or not.  In the asset case, you'd
>> associate mux assets with ehci-omap.0.
>>
>> Yesterday I studied the hub port code and have a couple of patches,
>> one normalizes the hub port device to have a stub driver.
>>
>> The other then puts hub port power state signalling into runtime_pm
>> handlers in the hub port device.  Until now, actually there's no
>> code in hub.c to switch off a port.
>
> Did you take a look at the most recent patches from Tianyu to add
> support to power off a port if a device is suspended?
>
> Start of the series:
> http://marc.info/?l=linux-usb&m=135314427413307&w=2
> Patch that adds power off on device suspend:
> http://marc.info/?l=linux-usb&m=135314431913321&w=2
>
> Tianyu also added some code to the xHCI host controller driver to call
> into the ACPI methods to power off a port when the USB hub driver clears
> the port power feature.

No I didn't know about it, I will study these along with pm_domain stuff 
thanks.

-Andy

-- 
Andy Green | TI Landing Team Leader
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