| Message ID | 9c78a6db02ac55f7af7371b417b6e414d2c3095b.1450188128.git.nsekhar@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
* Sekhar Nori <nsekhar@ti.com> [151215 06:26]: > 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@ti.com> Looks good to me, probably should get tagged Cc stable when committing: Acked-by: Tony Lindgren <tony@atomide.com> > --- > v3: add unlikely(), add profiling information > to commit message. > > v2: increment error irq counter, use pr_err_once, > add a comment on tips to debug spurious irq > condition. > > This patch results in a checkpatch warning about > extern definition of irq_err_count, but looks like > thats the prevalent method of accessing that counter. > > drivers/irqchip/irq-omap-intc.c | 27 ++++++++++++++++++++++++++- > 1 file changed, 26 insertions(+), 1 deletion(-) > > diff --git a/drivers/irqchip/irq-omap-intc.c b/drivers/irqchip/irq-omap-intc.c > index 8587d0f8d8c0..f6cb1b8bb981 100644 > --- 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, struct device_node *node) > 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 + * sorting is no longer active during the sorting (10 INTC 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); > } > > -- > 2.6.3 > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Thomas, On Tuesday 15 December 2015 08:58 PM, Tony Lindgren wrote: > * Sekhar Nori <nsekhar@ti.com> [151215 06:26]: >> 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@ti.com> > > Looks good to me, probably should get tagged Cc stable when > committing: > > Acked-by: Tony Lindgren <tony@atomide.com> Can you please apply this if it looks good? Thanks, Sekhar -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/irqchip/irq-omap-intc.c b/drivers/irqchip/irq-omap-intc.c index 8587d0f8d8c0..f6cb1b8bb981 100644 --- 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, struct device_node *node) 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); }
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@ti.com> --- v3: add unlikely(), add profiling information to commit message. v2: increment error irq counter, use pr_err_once, add a comment on tips to debug spurious irq condition. This patch results in a checkpatch warning about extern definition of irq_err_count, but looks like thats the prevalent method of accessing that counter. drivers/irqchip/irq-omap-intc.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-)