Subject: [PATCH v3 1/8] ARM/dts: omap2: Add McBSP entries for OMAP2420 and OMAP2430 SoC

From: [email-masked] (Tony Lindgren)
Date: Mon, 10 Sep 2012 09:01:05 -0700

* Peter Ujfalusi <[email-masked]> [120910 04:05]:
> Hi Benoit,
> 
> On 09/10/2012 11:07 AM, Benoit Cousson wrote:
> > Hi Tony,
> > 
> > On 09/08/2012 12:29 AM, Tony Lindgren wrote:
> >> * Peter Ujfalusi <[email-masked]> [120905 04:59]:
> >>> +
> >>> +	ocp {
> >>> +		mcbsp1: mcbsp at 48074000 {
> >>> +			compatible = "ti,omap2420-mcbsp";
> >>> +			reg = <0x48074000 0xff>;
> >>> +			reg-names = "mpu";
> >>> +			interrupts = <59>, /* TX interrupt */
> >>> +				     <60>; /* RX interrupt */
> >>> +			interrupt-names = "tx", "rx";
> >>> +			interrupt-parent = <&intc>;
> >>> +			ti,hwmods = "mcbsp1";
> >>> +		};
> >>> +
> >>> +		mcbsp2: mcbsp at 48076000 {
> >>> +			compatible = "ti,omap2420-mcbsp";
> >>> +			reg = <0x48076000 0xff>;
> >>> +			reg-names = "mpu";
> >>> +			interrupts = <62>, /* TX interrupt */
> >>> +				     <63>; /* RX interrupt */
> >>> +			interrupt-names = "tx", "rx";
> >>> +			interrupt-parent = <&intc>;
> >>> +			ti,hwmods = "mcbsp2";
> >>> +		};
> >>> +	};
> >>
> >> Hmm don't you need to specify the interrupt chip and offset for
> >> the interrupts here?
> > 
> > Mmm, I'm not sure to get your question, there is the link to the
> > interrupt-parent.
> > 
> > The interrupt number is relative to the parent interrupt domain. So even
> > if the INTC IRQ offset start at 32 instead of 0, DT IRQ mechanism will
> > convert that to the proper hwirq thanks to irqdomain.
> > In that case we should always provide interrupt number relative to the
> > interrupt controller HW number and not assuming any Linux IRQ number
> > offset like before.

Yes never mind, I was confused. We have #interrupt-cells = <1> and the
interrupt specifier is just the interrupt offset..

Regards,

Tony 

> > And in fact the interrupt-parent is not even needed, by default if will
> > look to the parent to get the interrupt-controller.
> 
> This is true, but it makes the 'code' a bit more readable if I (we) specify
> the interrupt-parent.
> 
> > 
> > Extract from [1]
> > 
> > interrupt-parent:
> > "Because the hierarchy of the nodes in the interrupt tree might not
> > match the device tree, the interrupt-parent property is available to
> > make the definition of an interrupt parent explicit.
> > The value is the phandle to the interrupt parent. If this property is
> > missing from a device, its interrupt parent is assumed to be its device
> > tree parent."
> > 
> > [1] http://www.power.org/resources/downloads/Power_ePAPR_APPROVED_v1.0.pdf
> > 
> > Regards,
> > Benoit
> > 
> 
> 
> -- 
> P?ter