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Re: [Qemu-devel] [PATCH 08/15] hw/arm_gic.c: lower IRQ only on changing
From: |
Paul Brook |
Subject: |
Re: [Qemu-devel] [PATCH 08/15] hw/arm_gic.c: lower IRQ only on changing of enable bit. |
Date: |
Fri, 9 Dec 2011 15:55:01 +0000 |
User-agent: |
KMail/1.13.7 (Linux/3.1.0-1-amd64; KDE/4.6.5; x86_64; ; ) |
> In previous version IRQ was lowered every time if enable bits were
> not set. If platform has splitted IRQ source to pass IRQ to two
> identical GICs simultaneously in first of which IRQ passing is
> enabled but in second is disabled, handling IRQ by second GIC would
> lower IRQ previously raised by first GIC.
> Linux kernel v3.0 faces this problem.
> The problem is avoided if IRQ is only lowered as result of
> transitioning enable bits to zeroes.
This is almost certainly wrong. IRQ lines are state based, not event based.
Re-asserting an existing level should always be a no-op.
My guess is your real bug it that your IRQ wiring is broken, and you have
multiple outputs connected to a single input. Don't do that. Ever. If you
need to connent multiple output pins to a single input pin then you need an
explicit device (e.g. an or gate) in between.
Paul
- [Qemu-devel] [PATCH 00/15 V2] ARM: Samsung Exynos4210-based boards support., Evgeny Voevodin, 2011/12/09
- [Qemu-devel] [PATCH 08/15] hw/arm_gic.c: lower IRQ only on changing of enable bit., Evgeny Voevodin, 2011/12/09
- Re: [Qemu-devel] [PATCH 08/15] hw/arm_gic.c: lower IRQ only on changing of enable bit.,
Paul Brook <=
- [Qemu-devel] [PATCH 04/15] hw/sysbus.h: Increase maximum number of device IRQs., Evgeny Voevodin, 2011/12/09
- [Qemu-devel] [PATCH 07/15] hw/arm_boot.c: Add new secondary CPU bootloader., Evgeny Voevodin, 2011/12/09
- [Qemu-devel] [PATCH 01/15] ARM: Samsung exynos421 0-based boards emulation, Evgeny Voevodin, 2011/12/09
- [Qemu-devel] [PATCH 03/15] ARM: exynos4210: UART support, Evgeny Voevodin, 2011/12/09
- [Qemu-devel] [PATCH 06/15] ARM: exynos4210: PWM support., Evgeny Voevodin, 2011/12/09
- [Qemu-devel] [PATCH 12/15] hw/exynos4210.c: Add LAN support for SMDKC210., Evgeny Voevodin, 2011/12/09
- [Qemu-devel] [PATCH 10/15] hw/exynos4210.c: Boot secondary CPU., Evgeny Voevodin, 2011/12/09
- [Qemu-devel] [PATCH 02/15] ARM: exynos4210: CMU support, Evgeny Voevodin, 2011/12/09
- [Qemu-devel] [PATCH 05/15] ARM: exynos4210: IRQ subsystem support., Evgeny Voevodin, 2011/12/09
- [Qemu-devel] [PATCH 11/15] hw/lan9118: Add basic 16-bit mode support., Evgeny Voevodin, 2011/12/09