linux-kernel - Re: [PATCH v4 4/4] gpio: pl061: enable interrupts with DT style binding

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Message-ID: <4F346228.5020300@gmail.com>
Date:	Thu, 09 Feb 2012 18:17:44 -0600
From:	Rob Herring <robherring2@...il.com>
To:	Shawn Guo <shawn.guo@...aro.org>
CC:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Grant Likely <grant.likely@...retlab.ca>,
	Thomas Gleixner <tglx@...utronix.de>, b-cousson@...com,
	Linus Walleij <linus.ml.walleij@...il.com>
Subject: Re: [PATCH v4 4/4] gpio: pl061: enable interrupts with DT style binding

On 02/09/2012 05:58 PM, Shawn Guo wrote:
> On Thu, Feb 09, 2012 at 04:03:10PM -0600, Rob Herring wrote:
>>
>> On 02/09/2012 02:04 PM, Shawn Guo wrote:
>>> On Fri, Feb 03, 2012 at 04:35:12PM -0600, Rob Herring wrote:
>>> ...
>>>> @@ -126,18 +127,16 @@ static void pl061_set_value(struct gpio_chip *gc, unsigned offset, int value)
>>>>  static int pl061_to_irq(struct gpio_chip *gc, unsigned offset)
>>>>  {
>>>>  	struct pl061_gpio *chip = container_of(gc, struct pl061_gpio, gc);
>>>> -
>>>> -	if (chip->irq_base <= 0)
>>>> -		return -EINVAL;
>>>> -
>>>> -	return chip->irq_base + offset;
>>>> +	if (!chip->irq_gc)
>>>> +		return -ENXIO;
>>>> +	return irq_find_mapping(chip->irq_gc->domain, offset);
>>>
>>> If I understand the driver correctly, it will add a linear domain for
>>> dt case.  Do you have code somewhere creating the mapping before this
>>> irq_find_mapping gets called here?  The reason I'm asking this is I
>>> have to call irq_create_mapping rather than irq_find_mapping here to
>>> get imx gpio driver working with linear domain, otherwise the
>>> irq_find_mapping call will fail.
>>>
>>
>> Right, the user has to call irq_of_parse_and_map (which calls
>> irq_create_mapping ultimately). Interrupts are allocated on demand. The
>> dts needs to declare the gpio controller as an interrupt-controller and
>> the node using the gpio line needs to set its interrupt parent and
>> interrupt connection
>>
> Yes, that's how dt users use irq.  But since I'm trying to make the
> imx gpio irq_domain as linear for both non-dt and dt users.  Calling
> irq_create_mapping here may make sense for me, since it will not
> require all these non-dt users change the way they use gpio irq.
> 

I wouldn't try to use linear for non-DT at this point.

> Even for dt users, there may have some case that can not work in the
> way we expect.
> 
> 	soc {
> 		#address-cells = <1>;
> 		#size-cells = <1>;
> 		compatible = "simple-bus";
> 		interrupt-parent = <&tzic>;
> 		ranges;
> 
> 		esdhc@...08000 { /* ESDHC2 */
> 			compatible = "fsl,imx51-esdhc";
> 			reg = <0x70008000 0x4000>;
> 			interrupts = <2>;
> 			cd-gpios = <&gpio1 6 0>;
> 			wp-gpios = <&gpio1 5 0>;
> 		};
> 	};
> 
> In above SD example, irq_of_parse_and_map will just work out the SD
> controller internal irq to tzic.  How can we work out the card-detection
> irq to gpio controller in the same way?
> 

That's the limitation in the interrupt binding. Normally, an interrupt
nexus is used for this.

Rob
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