On 08/20/2013 11:12 AM, Tomasz Figa wrote:
> On Tuesday 20 of August 2013 11:00:53 Stephen Warren wrote:
>> On 08/20/2013 07:52 AM, Tomasz Figa wrote:
>>> This patch updates description of device tree bindings for Exynos MCT
>>>
>>> (multicore timers). Namely:
>>> - added note about simplified specification of local timer interrupts,
>>>
>>> when using single per-processor interrupt for all local timers,
>>>
>>> - changed first example that was incorrectly suggesting that global
>>>
>>> timer interrupts are optional,
>>>
>>> - simplified example interrupt map,
>>> - added example showing simplified local timer interrupt
>>> specification.
>>>
>>> diff --git
>>> a/Documentation/devicetree/bindings/timer/samsung,exynos4210-mct.txt
>>> b/Documentation/devicetree/bindings/timer/samsung,exynos4210-mct.txt
>>>
>>> -Example 1: In this example, the system uses only the first global
>>> timer
>>> - interrupt generated by MCT and the remaining three global timer
>>> - interrupts are unused. Two local timer interrupts have been
>>> - specified.
>>> + For MCT block that uses a per-processor interrupt for local timers,
>>> such + as ones compatible with "samusng,exynos4412-mct", only one
>>> local timer
>> samsung is typo'd there.
>
> Oops. ;)
>
>>> +Example 2: In this example, the timer interrupts are connected to two
>>> separate + interrupt controllers. Hence, an interrupt-map is
>>> created to map + the interrupts to the respective interrupt
>>> controllers.
>>>
>>> mct@101C0000 {
>>>
>>> compatible = "samsung,exynos4210-mct";
>>> reg = <0x101C0000 0x800>;
>>>
>>> - interrupt-controller;
>>> - #interrups-cells = <2>;
>>>
>>> interrupt-parent = <&mct_map>;
>>>
>>> - interrupts = <0 0>, <1 0>, <2 0>, <3 0>,
>>> - <4 0>, <5 0>;
>>> + interrupts = <0>, <1>, <2>, <3>, <4>, <5>;
>>>
>>> mct_map: mct-map {
>>>
>>> - #interrupt-cells = <2>;
>>> + #interrupt-cells = <1>;
>>>
>>> #address-cells = <0>;
>>> #size-cells = <0>;
>>
>> I don't believe you need either of those two properties in a node solely
>> used as an interrupt map.
>
> Well, you don't need #size-cells, as it is not used for interrupt-map
> property.
>
> As for #address-cell property, you need it, as it defines how many cells
> are used in interrupt map specifier for unit address. See ePAPR 2.4.3.1 or
> [1] for a description of interrupt-map property format.
>
> [1] - http://devicetree.org/Device_Tree_Usage#Advanced_Interrupt_Mapping
Uggh. Yes, you're right.
>> Also, why not put the interrupt-map property directly into the main mct
>> node; I don't believe there's any requirement nor advantage to it being
>> a separate node.
>
> It is more readable, as you don't mix virtual (helper) properties, with
> those describing the hardware. Otherwise both ways are technically correct,
> but not for all cases, i.e. only when #address-cells and #interrupt-cells
> properties aren't used for device's own purposes.
Hmm. I see the argument.
>>> +Example 3: In this example, the IP contains four local timers, but
>>> using + a per-processor interrupt to handle them. Either all the
>>> local + timer interrupts can be specified, with the same interrupt
>>> specifier + value or just the first one.
>>
>> That sounds like it should be two separate examples.
>>
>> Actually, there's already a 2-timer example above using separate
>> interrupts, so why not make this example *just* be for the
>> single-interrupt case?
>
> Well, I wanted to show that both ways of specification would be equivalent
> here. If you insist on making it a single example, then I can send next
> version with this changed.
Oh! I didn't see the /* */ at all in the third example...
I think it'd be more obvious if you wrote the whole property out twice:
+ interrupts = <0 57 0>, <0 69 0>, <0 70 0>, <0 71 0>,
+ <0 42 0>/*, <0 42 0>, <0 42 0>, <0 42 0>*/;
+ /* or: */
+ interrupts = <0 57 0>, <0 69 0>, <0 70 0>, <0 71 0>,
+ <0 42 0>;
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