Messages in this thread | | | Date | Sat, 11 Jul 2015 17:26:44 +0200 | From | Noralf Trønnes <> | Subject | Re: [PATCH] irqchip: bcm2835: Add FIQ support |
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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.
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