[PATCH] [RFC] Fix level IRQ handling on Xilinx INTC with ARCH=powerpc

[PATCH] [RFC] Fix level IRQ handling on Xilinx INTC with ARCH=powerpc

[Sergey Temerkhanov]

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This fixes the missing acknowledge at the end of handle_level_irq().

It adds a field flags to struct irq_chip. If IRQ_CHIP_UNMASK_ACK is set in 
this field, acknowledge is performed before unmasking.

[-- Attachment #2: fix-level-irq-handling.patch --]
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diff -r 6b0915754563 arch/powerpc/sysdev/xilinx_intc.c
--- a/arch/powerpc/sysdev/xilinx_intc.c	Mon Jul 28 19:59:22 2008 +0400
+++ b/arch/powerpc/sysdev/xilinx_intc.c	Fri Aug 08 13:13:52 2008 +0400
@@ -73,6 +73,7 @@
 	.mask = xilinx_intc_mask,
 	.unmask = xilinx_intc_unmask,
 	.ack = xilinx_intc_ack,
+	.flags = IRQ_CHIP_UNMASK_ACK,
 };
 
 /*
@@ -107,8 +108,8 @@
 	}
 	regs = ioremap(res.start, 32);
 
-	printk(KERN_INFO "Xilinx intc at 0x%08LX mapped to 0x%p\n",
-		res.start, regs);
+	printk(KERN_INFO "Xilinx intc at 0x%p mapped to 0x%p\n",
+		(void *)res.start, regs);
 
 	/* Setup interrupt controller */
 	out_be32(regs + XINTC_IER, 0); /* disable all irqs */
diff -r 6b0915754563 include/linux/irq.h
--- a/include/linux/irq.h	Mon Jul 28 19:59:22 2008 +0400
+++ b/include/linux/irq.h	Fri Aug 08 13:13:52 2008 +0400
@@ -114,6 +114,9 @@
 	int		(*retrigger)(unsigned int irq);
 	int		(*set_type)(unsigned int irq, unsigned int flow_type);
 	int		(*set_wake)(unsigned int irq, unsigned int on);
+
+	unsigned int	flags;
+#define IRQ_CHIP_UNMASK_ACK	0x00000001
 
 	/* Currently used only by UML, might disappear one day.*/
 #ifdef CONFIG_IRQ_RELEASE_METHOD
diff -r 6b0915754563 kernel/irq/chip.c
--- a/kernel/irq/chip.c	Mon Jul 28 19:59:22 2008 +0400
+++ b/kernel/irq/chip.c	Fri Aug 08 13:13:52 2008 +0400
@@ -377,8 +377,12 @@
 
 	spin_lock(&desc->lock);
 	desc->status &= ~IRQ_INPROGRESS;
-	if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask)
-		desc->chip->unmask(irq);
+	if (!(desc->status & IRQ_DISABLED)) {
+		if (desc->chip->flags & IRQ_CHIP_UNMASK_ACK)
+			desc->chip->ack(irq);
+		if (desc->chip->unmask)
+			desc->chip->unmask(irq);
+	}
 out_unlock:
 	spin_unlock(&desc->lock);
 }

Re: [PATCH] [RFC] Fix level IRQ handling on Xilinx INTC with ARCH=powerpc

[Grant Likely]

On Mon, Aug 25, 2008 at 6:55 AM, Sergey Temerkhanov
<temerkhanov@yandex.ru> wrote:
> This fixes the missing acknowledge at the end of handle_level_irq().
>
> It adds a field flags to struct irq_chip. If IRQ_CHIP_UNMASK_ACK is set in
> this field, acknowledge is performed before unmasking.

Can this fix be handled in the XINTC controller driver itself?  This
patch unconditionally adds what is essentially a device specific fixup
to *every* Linux platform.  I cannot see that flying very far.

g.

Re: [PATCH] [RFC] Fix level IRQ handling on Xilinx INTC with ARCH=powerpc

[Sergey Temerkhanov]

On Monday 25 August 2008 18:26:54 Grant Likely wrote:
>This
> patch unconditionally adds what is essentially a device specific fixup
> to *every* Linux platform.  I cannot see that flying very far.
>

I know that. But without IRQ_CHIP_UNMASK_ACK set this fixup won'be applied so 
setups that are not affected should work as before.

This problem was already discussed before: 
http://www.nabble.com/Level-IRQ-handling-on-Xilinx-INTC-with-ARCH%3Dpowerpc-td18711173.html

Of course, I can just modify xilinx_intc_unmask() routine to perform 
acknowledge as I did before, but it seems a hack to me.