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. Now if your concern is the register_routable_domain_ops() then we are open to hear if there is any better way to do that. Thats why the series is still RFC. Regards, Santosh -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
