On Mar 24, 2009, at 4:13 PM, Johns Daniel wrote:
On Tue, Mar 24, 2009 at 3:54 PM, Kumar Gala
<ga...@kernel.crashing.org> wrote:
On Mar 24, 2009, at 3:24 PM, Johns Daniel wrote:
Could somebody please explain the declaration of the PCIe interrupts
in the device tree?
I was under the impression that PCIe interrupts in the PowerPC Linux
kernel default to using INTx signaling (vs. external IRQ pin assertion
and MSI signaling). Am I right?
If so, then do the interrupt-map lines in the DTS refer to the
internal IRQ used by Freescale processors to implement INTx virtual
wire interrupts?
For example, in the mpc8536ds.dts file, under "pci1: p...@ffe09000"
we have:
interrupt-map = <
/* IDSEL 0x0 */
0000 0 0 1 &mpic 4 1
0000 0 0 2 &mpic 5 1
0000 0 0 3 &mpic 6 1
0000 0 0 4 &mpic 7 1
>;
Are the 4, 5, 6, and 7 internal or external IRQs?
The .dts and linux make no distinction between internal & external
IRQs. This is a silly artifact of Freescale UMs. IRQ 0 starts at
offset 0x50000 and each 0x20 offset is another IRQ. So typically
External 0 == IRQ0, Internal 0 == IRQ16.
So this says that Ext 4, 5, 6, 7 and wired to INTA, INTB, INTC, INTD
for this particular PCIe controller.
When you say "wired", do you mean hard-wired?
Yes. The INTx emulation interrupts are hard-wired by the SoC on top
of the external IRQs.
If so, how would you specify and use INTx message interrupts?
Do you mean MSI or INTx emulation?
- k
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