linux-kernel - Re: [PATCHv2] Input: omap4-keypad: Add pinctrl support

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Message-ID: <5086D91A.5080109@firmworks.com>
Date:	Tue, 23 Oct 2012 07:51:22 -1000
From:	Mitch Bradley <wmb@...mworks.com>
To:	balbi@...com
CC:	Linus Walleij <linus.walleij@...aro.org>,
	devicetree-discuss@...ts.ozlabs.org,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
	Sourav Poddar <sourav.poddar@...com>,
	linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCHv2] Input: omap4-keypad: Add pinctrl support

Perhaps I misunderstood what you were suggesting.  I thought that, when
you said "explicitly manage all their resources", you meant that the
driver should know the platform-specific details about clocks and power
domains.  That is one possible interpretation of the word "explicit".

Now I see that you meant that the driver should explicitly call
abstracted functions.


On 10/23/2012 7:20 AM, Felipe Balbi wrote:
> HI,
> 
> On Tue, Oct 23, 2012 at 07:02:09AM -1000, Mitch Bradley wrote:
>> On 10/23/2012 12:03 AM, Felipe Balbi wrote:
>>> Hi,
>>>
>>> I much prefer having drivers explicitly manage all their resources,
>>> which would mean that pinctrl calls need to be done on probe() and, if
>>> necessary, during suspend()/resume().
>>
>>
>> Per-driver resource management is certainly convenient when you are
>> dealing with a single system, but it becomes difficult to maintain for
>> drivers that are shared among many platforms.
> 
> why ? look at drivers/usb/dwc3/, we're using that on OMAP, exynos, PCIe
> and a couple of different FPGA implementations inside TI. Not to mention
> what other licensees of that IP core might have internally.
> 
> So far no problesm with resources at all.
> 
> We have frameworks exactly to hide the differences.
> 
>> The industry trend for many years has been consolidation around a single
>> programming model per class of device.  For example, SDHCI, EHCI, ATA.
>> This trend will only accelerate, as the cost of developing controller IP
>> and associated drivers increases.  Such drivers need to be as
>> platform-agnostic as possible.
> 
> that's why we have pinctrl framework to abstract the details about pin
> muxing.
> 
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