Messages in this thread | | | Date | Mon, 25 Mar 2013 09:38:47 +0100 | From | Thomas Petazzoni <> | Subject | Re: [RFC 0/2] PCI: Introduce MSI chip infrastructure |
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Dear Thierry Reding,
Thanks for your feedback!
On Mon, 25 Mar 2013 08:58:10 +0100, Thierry Reding wrote:
> That sounds very much like one of the use-cases that were discussed. The > easiest solution would probably be to add an API to look up an MSI chip > from a DT phandle, so that the PCIe controller's device node could have > it as a property, somewhat like this: > > msi: interrupt-controller { > }; > > pcie-controller { > ... > marvell,msi = <&msi>; > ... > };
I'm not sure how to handle this msi interrupt controller with the main interrupt controller. For now, I have:
mpic: interrupt-controller@d0020000 { reg = <0xd0020a00 0x2d0>, <0xd0021070 0x58>; };
[...]
soc { interrupt-parent = <&mpic>; [...] };
And the MSI interrupt controller shares the same registers as the MPIC. So should it be something like:
interrupt-controller { reg = <0xd0020a00 0x2d0>, <0xd0021070 0x58>;
mpic { /* Not sure what to have here */ };
msi {
/* Here either */ }; };
soc { interrupt-parent = <&mpic>;
pcie-controller { marvell,msi = <&msi>; }; };
Or some other idea?
> Then add some basic infrastructure to register the MSI chip with a > global list, call that from the interrupt controller initialization: > > ... > msi_chip_add(&msi); > ... > > And finally look it up from the PCIe controller driver: > > node = of_parse_phandle(dev->of_node, "marvell,msi", 0); > if (node) > msi = of_find_msi_chip_by_node(node); > > That's roughly what other subsystems do. I wrote something similar once > for backlight devices, though the registration step (msi_chip_add) > wasn't necessary there since backlight devices all go into a common > struct class so class_find_device() can be used instead of going through > a separate registry.
Ok, that part sounds good to me. I'm still unsure about the DT representation, though (see above), and experience has shown that's it's a pretty good idea to discuss a little bit the DT representation before going on with some code :)
Thanks again for your feedback!
Thomas -- Thomas Petazzoni, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com
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