From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:56226) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TAsoq-0006Ai-37 for qemu-devel@nongnu.org; Sun, 09 Sep 2012 21:29:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TAsop-0003Fe-1N for qemu-devel@nongnu.org; Sun, 09 Sep 2012 21:29:44 -0400 Received: from qmta01.emeryville.ca.mail.comcast.net ([76.96.30.16]:51301) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TAsoo-0003CO-RD for qemu-devel@nongnu.org; Sun, 09 Sep 2012 21:29:42 -0400 From: Matthew Ogilvie Date: Sun, 9 Sep 2012 19:29:23 -0600 Message-Id: <1347240563-6212-2-git-send-email-mmogilvi_qemu@miniinfo.net> In-Reply-To: <1347240563-6212-1-git-send-email-mmogilvi_qemu@miniinfo.net> References: <1347240563-6212-1-git-send-email-mmogilvi_qemu@miniinfo.net> Subject: [Qemu-devel] [PATCH 2/2] KVM: i8259: refactor pic_set_irq level logic List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Paolo Bonzini , Jan Kiszka , Matthew Ogilvie , "Maciej W. Rozycki" , kvm@vger.kernel.org No change in functionality. Clarify that the only difference between level triggered and edge triggered interrupts is on the leading edge. Signed-off-by: Matthew Ogilvie --- arch/x86/kvm/i8259.c | 28 +++++++++++----------------- 1 file changed, 11 insertions(+), 17 deletions(-) diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c index b0c2346..d6c005c 100644 --- a/arch/x86/kvm/i8259.c +++ b/arch/x86/kvm/i8259.c @@ -95,26 +95,20 @@ static inline int pic_set_irq1(struct kvm_kpic_state *s, int irq, int level) { int mask, ret = 1; mask = 1 << irq; - if (s->elcr & mask) /* level triggered */ - if (level) { + if (level) { + if ((s->last_irr & mask) == 0 || /* edge for edge-triggered */ + (s->elcr & mask)) { /* or level triggered */ ret = !(s->irr & mask); s->irr |= mask; - s->last_irr |= mask; - } else { - s->irr &= ~mask; - s->last_irr &= ~mask; - } - else /* edge triggered */ - if (level) { - if ((s->last_irr & mask) == 0) { - ret = !(s->irr & mask); - s->irr |= mask; - } - s->last_irr |= mask; - } else { - s->irr &= ~mask; - s->last_irr &= ~mask; } + s->last_irr |= mask; + } else { + /* Dropping level clears the interrupt regardless of edge + * trigger vs level trigger. + */ + s->irr &= ~mask; + s->last_irr &= ~mask; + } return (s->imr & mask) ? -1 : ret; } -- 1.7.10.2.484.gcd07cc5