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

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Message-ID: <513F5298.6000500@pengutronix.de>
Date:	Tue, 12 Mar 2013 17:06:48 +0100
From:	Marc Kleine-Budde <mkl@...gutronix.de>
To:	Roger Quadros <rogerq@...com>
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 04:20 PM, Roger Quadros wrote:
> 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?

You're using -EPROBE_DEFER, that's all perfectly fine.

>>> 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].

Okay, I wrongly assumed that there wouldn't be added any new features to
the old non-DT board files.

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

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
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