This is a note to let you know that I've just added the patch titled
irqchip/omap-intc: Add support for spurious irq handling
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
irqchip-omap-intc-add-support-for-spurious-irq-handling.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d3b421cd07e4c0d4d6c0bbd55ca169c054fc081d Mon Sep 17 00:00:00 2001
From: Sekhar Nori <nsekhar@xxxxxx>
Date: Tue, 15 Dec 2015 19:56:12 +0530
Subject: irqchip/omap-intc: Add support for spurious irq handling
From: Sekhar Nori <nsekhar@xxxxxx>
commit d3b421cd07e4c0d4d6c0bbd55ca169c054fc081d upstream.
Under some conditions, irq sorting procedure used by INTC can go wrong
resulting in a spurious irq getting reported.
If this condition is not handled, it results in endless stream of:
unexpected IRQ trap at vector 00
messages from ack_bad_irq()
Handle the spurious interrupt condition in omap-intc driver to prevent this.
Measurements using kernel function profiler on AM335x EVM running at 720MHz
show that after this patch omap_intc_handle_irq() takes about 37.4us against
34us before this patch.
Signed-off-by: Sekhar Nori <nsekhar@xxxxxx>
Acked-by: Tony Lindgren <tony@xxxxxxxxxxx>
Cc: John Ogness <john.ogness@xxxxxxxxxxxxx>
Cc: Felipe Balbi <balbi@xxxxxx>
Cc: Jason Cooper <jason@xxxxxxxxxxxxxx>
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Link: http://lkml.kernel.org/r/9c78a6db02ac55f7af7371b417b6e414d2c3095b.1450188128.git.nsekhar@xxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/irqchip/irq-omap-intc.c | 27 ++++++++++++++++++++++++++-
1 file changed, 26 insertions(+), 1 deletion(-)
--- a/drivers/irqchip/irq-omap-intc.c
+++ b/drivers/irqchip/irq-omap-intc.c
@@ -47,6 +47,7 @@
#define INTC_ILR0 0x0100
#define ACTIVEIRQ_MASK 0x7f /* omap2/3 active interrupt bits */
+#define SPURIOUSIRQ_MASK (0x1ffffff << 7)
#define INTCPS_NR_ILR_REGS 128
#define INTCPS_NR_MIR_REGS 4
@@ -330,11 +331,35 @@ static int __init omap_init_irq(u32 base
static asmlinkage void __exception_irq_entry
omap_intc_handle_irq(struct pt_regs *regs)
{
+ extern unsigned long irq_err_count;
u32 irqnr;
irqnr = intc_readl(INTC_SIR);
+
+ /*
+ * A spurious IRQ can result if interrupt that triggered the
+ * sorting is no longer active during the sorting (10 INTC
+ * functional clock cycles after interrupt assertion). Or a
+ * change in interrupt mask affected the result during sorting
+ * time. There is no special handling required except ignoring
+ * the SIR register value just read and retrying.
+ * See section 6.2.5 of AM335x TRM Literature Number: SPRUH73K
+ *
+ * Many a times, a spurious interrupt situation has been fixed
+ * by adding a flush for the posted write acking the IRQ in
+ * the device driver. Typically, this is going be the device
+ * driver whose interrupt was handled just before the spurious
+ * IRQ occurred. Pay attention to those device drivers if you
+ * run into hitting the spurious IRQ condition below.
+ */
+ if (unlikely((irqnr & SPURIOUSIRQ_MASK) == SPURIOUSIRQ_MASK)) {
+ pr_err_once("%s: spurious irq!\n", __func__);
+ irq_err_count++;
+ omap_ack_irq(NULL);
+ return;
+ }
+
irqnr &= ACTIVEIRQ_MASK;
- WARN_ONCE(!irqnr, "Spurious IRQ ?\n");
handle_domain_irq(domain, irqnr, regs);
}
Patches currently in stable-queue which might be from nsekhar@xxxxxx are
queue-4.4/irqchip-omap-intc-add-support-for-spurious-irq-handling.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html