Hi Rob, On Tue, 13 Jan 2015 21:26:42 -0600 Rob Herring <robherring2@xxxxxxxxx> wrote: > On Tue, Jan 13, 2015 at 12:46 PM, Boris Brezillon > <boris.brezillon@xxxxxxxxxxxxxxxxxx> wrote: > > Some interrupt controllers are multiplexing several peripheral IRQs on > > a single interrupt line. > > While this is not a problem for most IRQs (as long as all peripherals > > request the interrupt with IRQF_SHARED flag set), multiplexing timers and > > other type of peripherals will generate a WARNING (mixing IRQF_NO_SUSPEND > > and !IRQF_NO_SUSPEND is prohibited). > > > > Create a dumb irq demultiplexer which simply forwards interrupts to all > > peripherals (exactly what's happening with IRQ_SHARED) but keep a unique > > irq number for each peripheral, thus preventing the IRQF_NO_SUSPEND > > and !IRQF_NO_SUSPEND mix on a given interrupt. > > This really seems like a work-around for how IRQF_SHARED works. It > seems like what is really desired is just per handler disabling. Like what I proposed here [1] ? > It is > fragile in that devices can deadlock the system if the drivers don't > disable the interrupt source before calling disable_irq. Not exactly deadlock since spurious interrupt detection is implemented, but yes, things won't work as expected. > But unlike > IRQF_SHARED, there is nothing explicit in the driver indicating it is > designed to work properly with a shared interrupt line. > > I see no reason to accept this into DT either. We already can support > shared lines and modeling an OR gate as an interrupt controller is > pointless. Okay, I guess I'll let DT and irq maintainers decide what is preferable here (I already spent much time than I first expected to remove this warning in a proper way). Best Regards, Boris [1]https://lkml.org/lkml/2014/12/15/552 -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com -- 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
