Messages in this thread | | | Date | Mon, 13 Jul 2015 22:50:50 -0600 | From | Stephen Warren <> | Subject | Re: [PATCH] irqchip: bcm2835: Add FIQ support |
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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?
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