Hi Thomas, On Tuesday 01 October 2013 08:37 PM, Santosh Shilimkar wrote: > On Tuesday 01 October 2013 10:53 AM, Rob Herring wrote: >> On 10/01/2013 08:57 AM, Santosh Shilimkar wrote: >>> On Tuesday 01 October 2013 09:48 AM, Rob Herring wrote: >>>> On 10/01/2013 06:13 AM, Sricharan R wrote: >>>>> Hi, >>>>> >>>>> On Monday 30 September 2013 08:39 PM, Rob Herring wrote: >>>>>> On 09/30/2013 08:59 AM, Sricharan R wrote: >>>>>>> Some socs have a large number of interrupts requests to service >>>>>>> the needs of its many peripherals and subsystems. All of the interrupt >>>>>>> requests lines from the subsystems are not needed at the same >>>>>>> time, so they have to be muxed to the controllers appropriately. >>>>>>> In such places a interrupt controllers are preceded by an >>>>>>> IRQ CROSSBAR that provides flexibility in muxing the device interrupt >>>>>>> requests to the controller inputs. >>>>>>> >>>>>>> This series models the peripheral interrupts that can be routed through >>>>>>> the crossbar to the GIC as 'routable-irqs'. The routable irqs are added >>>>>>> in a separate linear domain inside the GIC. The registered routable domain's >>>>>>> callback are invoked as a part of the GIC's callback, which in turn should >>>>>>> allocate a free irq line and configure the IP accordingly. So every peripheral >>>>>>> in the dts files mentions the fixed crossbar number as its interrupt. A free >>>>>>> gic line for that gets allocated and configured when the peripheral's interrupt >>>>>>> is mapped. >>>>>>> >>>>>>> The minimal crossbar driver to track and allocate free GIC lines and configure the >>>>>>> crossbar is added here, along with the DT bindings. >>>>>> Seems like interrupt-map property is what you need here. >>>>>> >>>>>> http://devicetree.org/Device_Tree_Usage#Advanced_Interrupt_Mapping >>>>>> >>>>>> Versatile Express also has an example. >>>>> OK, but the idea was not to tie up the crossbar<->interrupt numbers at the >>>>> DTS level, but to assign it dynamically during runtime. This was one of the >>>>> comments that came up with first crossbar support patches, which was assigning a >>>>> interrupt line to crossbar number in the DTS and setting it up in crossbar probe. >>>> Is there an actual usecase on a single h/w design that you run out of >>>> interrupts and it is a user decision which interrupts to use? >>>> >>> Yes. There are 240 peripheral interrupts connected out of which 160 can >>> be used in this specific case. >> Yes, I understand the SOC connections. That does not answer my question. >> The 240 interrupts are likely to be limited to fewer by board design, >> pinmuxing, etc. >> > yes limited by different board designs ... > >> How do you handle the 161st interrupt request? Will never happen? Just >> rely on the random driver probe ordering? >> > Well the board dts are expected to provide the peripheral support info to optimise it. > If a board actually has more than 160 peripherals available then in that > case the 161 interrupt will not be mapped. > >>>> You could fill in the interrupt-map at run-time. It would have to be >>>> early (bootloader or early kernel init) and can't be at request_irq time. >>>> >>> Well all options are tried before coming up to the $subject solution. >>> It was suggested by Thomas in the last review. >>> >>>>> https://lkml.org/lkml/2013/7/18/416 >>>>> >>>>> Since this approach of assigning in DTS was opposed, we moved to IRQCHIP and >>>>> that did not go as well. Finally was asked to handle this as a part of GIC driver with >>>>> a separate domain. >>>>> >>>>> http://www.spinics.net/lists/linux-omap/msg97085.html >>>> This has nothing to do with the GIC, so it does not belong there. >>>> >>> Well the router makes connections from peripheral to GIC. Thomas can >>> better explain it but I think since its doing irq routing for GIC on >>> a given hardware, I don't see any issue having some generic map/unmap >>> function in GIC. The actual implementation is still outside of GIC. >> I read Thomas' reply as don't put this crap in his code. >> > That was for the IRQCHIP based approach and as part of that review > Thomas suggested why not irqdomain and suggested a prototype code > as well. > >> You can call it generic, but it is not. It is specific to the GIC and >> looks like an abuse of irqdomains to me. Look where the function >> declaration for register_routable_domain_ops is. >> > I am not sure why you call it abuse of irqdomain since the map/unmap > are exactly the interfaces where the logical to physical irq > connections are made. Look at existing GIC code as well. I still > let Thomas give his expert comment whether it is abusive because it > it was, am sure he wouldn't have suggested that. Is this inline with what you were suggesting and is this approach fine ? Regards, Sricharan -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
