linux-kernel - Re: [PATCH 1/8] usb: phy: nop: Add some parameters to platform data

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Date:	Tue, 12 Mar 2013 17:20:20 +0200
From:	Roger Quadros <rogerq@...com>
To:	Marc Kleine-Budde <mkl@...gutronix.de>
CC:	<balbi@...com>, <tony@...mide.com>, <mark.rutland@....com>,
	<linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
	<linux-omap@...r.kernel.org>,
	<devicetree-discuss@...ts.ozlabs.org>,
	"Ujfalusi, Peter" <peter.ujfalusi@...com>
Subject: Re: [PATCH 1/8] usb: phy: nop: Add some parameters to platform data

On 03/12/2013 04:42 PM, Marc Kleine-Budde wrote:
> On 03/12/2013 03:28 PM, Roger Quadros wrote:
>> On 03/12/2013 04:17 PM, Marc Kleine-Budde wrote:
>>> On 03/12/2013 03:12 PM, Roger Quadros wrote:
>>>> On 03/12/2013 01:54 PM, Marc Kleine-Budde wrote:
>>>>> On 03/12/2013 12:24 PM, Roger Quadros wrote:
>>>>>> Add clk_rate parameter to platform data. If supplied, the
>>>>>> NOP phy driver will program the clock to that rate during probe.
>>>>>>
>>>>>> Also add 2 flags, needs_vcc and needs_reset.
>>>>>> If the flag is set and the regulator couldn't be found
>>>>>> then the driver will bail out with -EPROBE_DEFER.
>>>>>
>>>>> Is there a platform which fills out pdata.needs_vcc and
>>>>> pdata.needs_reset? IMHO it makes no sense to add features for the non DT
>>>>> case, if there isn't any user for it.
>>>>>
>>>>
>>>> There can be a user in the non DT case as well. Consider the following example:
>>>
>>> I'm just saying, let the implementation up to a real user for the non DT
>>> case. Beagleboard is ARM and there's no point of implementing non DT
>>> fall backs for ARM, IMHO.
>>>
>>
>> Why do you say so?
>>
>> It doesn't depend on the CPU architecture. It depends on how the board designer
>> wired the board. A non ARM platform could also face the same problem as beagle.
> 
> Using -EPROBE_DEFER ist the way to solve the problem.

did you mean isn't? If you did then what is the other option?
> 
>> It is not a non DT fallback. I believe many are still using non DT boot and it
>> needs to work at least till we move all functionality to purely DT.
> 
> From my point of view, it makes no sense today to implement new features
> which have a fallback for the non-DT case, if there isn't a real user of
> this feature. So IMHO don't add needs_vcc and needs_reset flags to the
> pdata, just take the information from the DT. As soon as there is a
> non-DT user of this feature she/he can implement it or even better
> switch to DT.

Adding Peter to the loop. I faintly remember him mentioning this issue before
for beagle. We really need the deferred probe mechanism or we need to resort
to device registering order.

The first user for needs_vcc flag will be the beagleboard file. I just didn't
implement it in this patch [1].

On second thoughts, since [1] does work on beagleboard without requiring the
needs_vcc flag, I think we can just live without it.

Felipe, Peter, what do you think?

cheers,
-roger

[1] https://lkml.org/lkml/2013/3/12/244
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