On 07/14/2015 05:48 AM, Noralf Trønnes wrote: > Den 14.07.2015 06:50, skrev Stephen Warren: >> On 07/11/2015 09:26 AM, Noralf Trønnes wrote: >>> Den 11.07.2015 06:09, skrev Stephen Warren: >>>> (Sorry for the slow reply; I was on vacation) >>>> >>>> On 06/18/2015 07:32 AM, Noralf Trønnes wrote: >>>>> Den 18.06.2015 04:26, skrev Stephen Warren: >>>>>> On 06/12/2015 11:26 AM, Noralf Trønnes wrote: >>>>>>> Add a duplicate irq range with an offset on the hwirq's so the >>>>>>> driver can detect that enable_fiq() is used. >>>>>>> Tested with downstream dwc_otg USB controller driver. >>>>>> This basically looks OK, but a few comments/thoughts: >>>>>> b) Doesn't the driver need to refuse some operation (handler >>>>>> registration, IRQ setup, IRQ enable, ...?) for more than 1 IRQ in the >>>>>> FIQ range, since the FIQ control register only allows routing 1 >>>>>> IRQ to >>>>>> FIQ. >>>>> claim_fiq() protects the FIQ. See d) answer below. >>>> That assumes the IRQ is "accessed" via the fiq-specific APIs. Since >>>> this >>>> patch changes the IRQ domain from having n IRQs to having 2*n IRQs, and >>>> doesn't do anything special to prevent clients from using IRQs n..2n-1 >>>> via the existing IRQ APIs, it's quite possible the a buggy client >>>> would. >>> Yes, but doesn't this apply to all irq use, using the wrong one doesn't >>> work. >>> If FIQ's where in more common use, we might have seen a FIQ IRQ flag >>> instead >>> of special FIQ irqs. >>> >>>> (From another email): >>>>>>> c) The DT binding needs updating to describe the extra IRQs: >>>>>>> >>>>>>>> Documentation/devicetree/bindings/interrupt-controller/brcm,bcm28armctrl-ic.txt >>>>>>>> >>>>>>>> >>>>>> Ok. >>>>> I have seconds thoughts on this: >>>>> This patch does not change the DT bindings so I don't see what update >>>>> I should make. This patch only adds support for the Linux way of >>>>> handling FIQ's through enable_fiq(). It doesn't change how interrupts >>>>> are described in the DT. >>>> The intention of the patch may not be to expand the set of IRQs >>>> available via DT, but it does in practice. I think you need to add a >>>> custom of_xlate for the IRQ domain to ensure that only IRQs 0..n-1 can >>>> be translated from DT, and not IRQs n..2n-1. If you do that, then I >>>> agree that no DT binding update should be required. >>> armctrl_xlate() maps to the same hwirqs as before. This patch adds a >>> new range of hwirqs at the end of the "real" hwirq range. >>> It's not possible to get to these FIQ shadow hwirqs through DT. >> What prevents a DT from (incorrectly) referencing the extra hwirqs? > > armctrl_xlate() has these limits: > > if (WARN_ON(intspec[0] >= NR_BANKS)) > if (WARN_ON(intspec[1] >= IRQS_PER_BANK)) > if (WARN_ON(intspec[0] == 0 && intspec[1] >= NR_IRQS_BANK0)) > > Thus the maximum values allowed are: > intspec[0]: (NR_BANKS - 1) = 2 > intspec[1]: (IRQS_PER_BANK - 1) = 31 > > This gives a maximum hwirq: > *out_hwirq = MAKE_HWIRQ(intspec[0], intspec[1]); > *out_hwirq = (2 << 5) | 31 = 95 > > The FIQ shadow hwirq range starts at 96: > irq = irq_create_mapping(intc.domain, MAKE_HWIRQ(b, i) + NUMBER_IRQS); > > NUMBER_IRQS = MAKE_HWIRQ(NR_BANKS, 0) = 96
Great, thanks for the explanation. That should be fine then. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/