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    SubjectRe: [PATCH 1/3] misc: Add crossbar driver
    * Santosh Shilimkar <santosh.shilimkar@ti.com> [130813 06:35]:
    > On Tuesday 13 August 2013 04:10 AM, Tony Lindgren wrote:
    > > * Santosh Shilimkar <santosh.shilimkar@ti.com> [130724 12:06]:
    > >> On Wednesday 24 July 2013 02:51 PM, Nishanth Menon wrote:
    > >>> On 07/24/2013 01:43 PM, Sricharan R wrote:
    > >>>> On Wednesday 24 July 2013 10:17 PM, Nishanth Menon wrote:
    > >>>>> On 07/24/2013 11:38 AM, Santosh Shilimkar wrote:
    > >>>>>> On Wednesday 24 July 2013 12:08 PM, Nishanth Menon wrote:
    > >>>>>>> That said, maybe a intermediate pinctrl approach might be more pragmatic and less theoretically flexible.
    > >>>>>>> an option might be to "statically allocate" default number of interrupts to a domain - example:
    > >>>>>>> * GIC IRQ 72->78 allotted to UARTs
    > >>>>>>> * pinctrl mapping provided for those but only 6 can be used (rest are marked status="disabled" as default) at any given time (choice of pinctrl option determines GIC interrupt line to use)
    > >>>>>>> * All modules will have a pinctrl definition to have a mapping - to avoid bootloader overriding default cross bar setting in ways un-expected by kernel.
    > >>>>>>>
    > >>>>>>> Does that sound fair trade off?
    > >>>>>> This sounds better. That way we can get all the devices in the DT at least.
    > >>>>>
    > >>>>> Fair enough - if Linus and Tony are still ok with this approach to the problem, seeing a patch series with the effect would be beneficial.
    > >>>>>
    > >>>> Ok, i will use this idea of certain number interrupts to groups.
    > >>>> Yes on DRA7XX, we have about 160 gic lines and 320 irq crossbar device inputs contending for it.
    > >>>> 1:2 and fully arbitrary. But will we be really exhausting them ?
    > >>>>
    > >>> Depends on how we allocate :). The default arbitary allocation can be made more logical in your series ofcourse :).
    > >>>
    > >> I would just most logical peripherals rather than providing every single
    > >> IP connected to cross bar. Otherwise we will end up wth hwmod like
    > >> scenario where now started removing the unused stuff because of
    > >> maintenance and loc issues ;-)
    > >
    > > Sorry for the delay on this, I think the best way to set this up
    > > is as a separate drivers/irqchip controller. Then just map the
    > > configured interrupts for the board with interrupt-map and
    > > interrupt-map-mask binding. No need to stuff all the SoC specific
    > > maps to the .dts, just the ones used for the board.
    > >
    > Interrupt mask/unmask, really ? Thats like abusing those irqchip
    > hooks completely. Your point is to just setup events which we need
    > and thats what I also suggested. But the use of irqchip hooks is
    > certainly not the right idea since they are for masking/unmasking
    > interrupts in running system and not for joining the interrupt
    > line which needs to happen once during probe.

    Well if it's an interrupt controller. Doing a chained IRQ pinctrl
    driver might work too. But yes, the idea with interrupt-map was
    to only map what's used rather than have data for each SoC.

    Regards,

    Tony


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