On 14/02/19 14:52, Marc Zyngier wrote: > On Thu, 14 Feb 2019 10:55:10 +0000, > Roger Quadros <rogerq@xxxxxx> wrote: >> >> >> On 14/02/19 10:37, Linus Walleij wrote: >>> On Thu, Feb 14, 2019 at 4:13 AM Suman Anna <s-anna@xxxxxx> wrote: >>>> [Me] >>> >>>>> To be able to use hierarchical interrupt domain in the kernel, the top >>>>> interrupt controller must use the hierarchical (v2) irqdomain, so >>>>> if this is anything else than the ARM GIC it will be an interesting >>>>> undertaking to handle this. >>>> >>>> These are interrupt lines coming towards the host processor running >>>> Linux and are directly connected to the ARM GIC. This INTC module is >>>> actually an PRUSS internal interrupt controller that can take in 64 (on >>>> most SoCs) external events/interrupt sources and multiplexing them >>>> through two layers of many-to-one events-to-intr channels & >>>> intr-channels-to-host interrupts. Couple of the host interrupts go to >>>> the PRU cores themselves while the remaining ones come out of the IP to >>>> connect to other GICs in the SoC. >>> >>> If the muxing is static (like set up once at probe) so that while >>> the system is running, there is one and one only event mapped to >>> the GIC from the component below it, then it is hierarchical. >> >> This is how it looks. >> >> [GIC]<---8---[INTC]<---64---[events from peripherals] >> >> The 8 interrupt lines from INTC to the GIC are 1:1 mapped and fixed >> per SoC. The muxing between 64 inputs to INTC and its 8 outputs are >> programmable and might not necessarily be static per boot/probe as >> it depends on what firmware is loaded on the PRU. > > But the point is that at any given time, there are at most 8 out of 64 > inputs that are used, right? You *never* end-up with two (or more) of > these "events" being multiplexed on a single output line. > Since the INTC's internal logic allows assigning more than one event each outputs, at most all 64 events can be assigned to one output or distributed among the 8 outputs. > If these assertions do hold, then your design is typical of a > hierarchy, for which we have countless examples in the tree (including > for some TI HW). OK. Suman, Andrew, Lokesh, thoughts? -- cheers, -roger Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
