On Thu, 2011-01-06 at 15:31 -0800, Kevin D. Kissell wrote:
> On 01/06/11 12:23, Anoop P A wrote:
>
> I'm sure I've said this before, and it's in various comments in the SMTC
> code, but remember, one of the main problems that the SMTC kernel
> had to solve was to prevent all TCs of a VPE from "convoying" after every
> interrupt. The way this is done is that the interrupt vector code, before
> clearing EXL, masks off the Status.IM bit associated with the incoming
> interrupt. Of course, to get another interrupt from the same source
> (or collection of sources), that IM bit needs to be restored. The "correct"
> mechanism for this is by having the appropriate irq_hwmask[] value set,
> so that smtc_im_ack_irq(), which should be invoked on an irq "ack()"
> (meaning that the source has been quenched and any new occurrence
> should be considered a new interrupt), will restore the bit in Status.
> This function got moved around a bit in the various SMTC prototypes,
> but it proved least intrusive to put it into the xxx_mask_and_ack()
> functions
> for the interrupt controllers - see irq-msc01.c and i8259.c. If you haven't
> done the same in any equivalent code for a different on-chip controller,
> you'll definitely have problems.
>
> The Backstop scheme works OK for peripheral interrupts that didn't
> have an appropriate irq_hwmask[] value set up, but clock interrupts
> don't follow the same code paths and can't depend on the backstop.
Ok. Well thanks much for your detailed explanation. Well I hope I found
the root cause . smtc_clockevent_init() was overriding irq_hwmask even
if are using platform specific get_c0_compare_int. With following patch
everything seems to be working for me.
------------------------------------------------------------------------
diff --git a/arch/mips/kernel/cevt-smtc.c b/arch/mips/kernel/cevt-smtc.c
index 2e72d30..a25fc59 100644
--- a/arch/mips/kernel/cevt-smtc.c
+++ b/arch/mips/kernel/cevt-smtc.c
@@ -310,9 +310,14 @@ int __cpuinit smtc_clockevent_init(void)
return 0;
/*
* And we need the hwmask associated with the c0_compare
- * vector to be initialized.
+ * vector to be initialized. However incase of platform
+ * specific get_co_compare_int, don't override irq_hwmask
+ * expect platform code to set a valid mask value.
*/
- irq_hwmask[irq] = (0x100 << cp0_compare_irq);
+
+ if (!get_c0_compare_int)
+ irq_hwmask[irq] = (0x100 << cp0_compare_irq);
+
if (cp0_timer_irq_installed)
return 0;
-----------------------------------------------------------------------
Attaching my msp_ir_cic.c . Kindly have a look if possible.
Thanks
Anoop
>
> Regards,
>
> Kevin K.
/*
* Copyright 2010 PMC-Sierra, Inc, derived from irq_cpu.c
*
* This file define the irq handler for MSP CIC subsystem interrupts.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*/
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/bitops.h>
#include <linux/irq.h>
#include <asm/mipsregs.h>
#include <asm/system.h>
#include <msp_cic_int.h>
#include <msp_regs.h>
/*
* External API
*/
extern void msp_per_irq_init(void);
extern void msp_per_irq_dispatch(void);
/*
* Convenience Macro. Should be somewhere generic.
*/
#define get_current_vpe() \
((read_c0_tcbind() >> TCBIND_CURVPE_SHIFT) & TCBIND_CURVPE)
#ifdef CONFIG_SMP
#define LOCK_VPE(flags, mtflags) \
do { \
local_irq_save(flags); \
mtflags = dmt(); \
} while (0)
#define UNLOCK_VPE(flags, mtflags) \
do { \
emt(mtflags); \
local_irq_restore(flags);\
} while (0)
#define LOCK_CORE(flags, mtflags) \
do { \
local_irq_save(flags); \
mtflags = dvpe(); \
} while (0)
#define UNLOCK_CORE(flags, mtflags) \
do { \
evpe(mtflags); \
local_irq_restore(flags);\
} while (0)
#else
#define LOCK_VPE(flags, mtflags)
#define UNLOCK_VPE(flags, mtflags)
#endif
/* ensure writes to cic are completed */
static inline void cic_wmb(void)
{
const volatile void __iomem *cic_mem = CIC_VPE0_MSK_REG;
volatile u32 dummy_read;
wmb();
dummy_read = __raw_readl(cic_mem);
dummy_read++;
}
static inline void unmask_cic_irq(unsigned int irq)
{
volatile u32 *cic_msk_reg = CIC_VPE0_MSK_REG;
int vpe;
#ifdef CONFIG_SMP
unsigned int mtflags;
unsigned long flags;
/*
* Make sure we have IRQ affinity. It may have changed while
* we were processing the IRQ.
*/
if (!cpumask_test_cpu(smp_processor_id(), irq_desc[irq].affinity))
return;
#endif
vpe = get_current_vpe();
LOCK_VPE(flags, mtflags);
cic_msk_reg[vpe] |= (1 << (irq - MSP_CIC_INTBASE));
UNLOCK_VPE(flags, mtflags);
cic_wmb();
}
static inline void mask_cic_irq(unsigned int irq)
{
volatile u32 *cic_msk_reg = CIC_VPE0_MSK_REG;
int vpe = get_current_vpe();
#ifdef CONFIG_SMP
unsigned long flags, mtflags;
#endif
LOCK_VPE(flags, mtflags);
cic_msk_reg[vpe] &= ~(1 << (irq - MSP_CIC_INTBASE));
UNLOCK_VPE(flags, mtflags);
cic_wmb();
}
static inline void msp_cic_irq_ack(unsigned int irq)
{
mask_cic_irq(irq);
/*
* Only really necessary for 18, 16-14 and sometimes 3:0
* (since these can be edge sensitive) but it doesn't
* hurt for the others
*/
*CIC_STS_REG = (1 << (irq - MSP_CIC_INTBASE));
smtc_im_ack_irq(irq);
}
static void msp_cic_irq_end(unsigned int irq)
{
if (!(irq_desc[irq].status & (IRQ_DISABLED | IRQ_INPROGRESS)))
unmask_cic_irq(irq);
}
#ifdef CONFIG_SMP
static inline int msp_cic_irq_set_affinity(unsigned int irq,
const struct cpumask *cpumask)
{
int cpu;
unsigned long flags;
unsigned int mtflags;
unsigned long imask = (1 << (irq - MSP_CIC_INTBASE));
volatile u32 *cic_mask = (volatile u32 *)CIC_VPE0_MSK_REG;
/* timer balancing should be disabled in kernel code */
BUG_ON(irq == MSP_INT_VPE0_TIMER || irq == MSP_INT_VPE1_TIMER);
LOCK_CORE(flags, mtflags);
/* enable if any of each VPE's TCs require this IRQ */
for_each_online_cpu(cpu) {
if (cpumask_test_cpu(cpu, cpumask))
cic_mask[cpu] |= imask;
else
cic_mask[cpu] &= ~imask;
}
UNLOCK_CORE(flags, mtflags);
return 0;
}
#endif
static struct irq_chip msp_cic_irq_controller = {
.name = "MSP_CIC",
.mask = msp_cic_irq_ack,
.mask_ack = msp_cic_irq_ack,
.unmask = unmask_cic_irq,
.ack = msp_cic_irq_ack,
.end = msp_cic_irq_end,
#ifdef CONFIG_SMP
.set_affinity = msp_cic_irq_set_affinity,
#endif
};
void __init msp_cic_irq_init(void)
{
int i;
/* Mask/clear interrupts. */
*CIC_VPE0_MSK_REG = 0x00000000;
*CIC_VPE1_MSK_REG = 0x00000000;
*CIC_STS_REG = 0xFFFFFFFF;
/*
* The MSP7120 RG and EVBD boards use IRQ[6:4] for PCI.
* These inputs map to EXT_INT_POL[6:4] inside the CIC.
* They are to be active low, level sensitive.
*/
*CIC_EXT_CFG_REG &= 0xFFFF8F8F;
/* initialize all the IRQ descriptors */
for (i = MSP_CIC_INTBASE ; i < MSP_CIC_INTBASE + 32 ; i++) {
set_irq_chip_and_handler(i, &msp_cic_irq_controller,
handle_level_irq);
#ifdef CONFIG_MIPS_MT_SMTC
/* Mask of CIC interrupt */
irq_hwmask[i] = C_IRQ4;
#endif
}
/* Initialize the PER interrupt sub-system */
msp_per_irq_init();
}
/* CIC masked by CIC vector processing before dispatch called */
void msp_cic_irq_dispatch(void)
{
volatile u32 *cic_msk_reg = (volatile u32 *)CIC_VPE0_MSK_REG;
u32 cic_mask;
u32 pending;
int cic_status = *CIC_STS_REG;
cic_mask = cic_msk_reg[get_current_vpe()];
pending = cic_status & cic_mask;
if (pending & (1 << (MSP_INT_VPE0_TIMER - MSP_CIC_INTBASE))) {
do_IRQ(MSP_INT_VPE0_TIMER);
} else if (pending & (1 << (MSP_INT_VPE1_TIMER - MSP_CIC_INTBASE))) {
do_IRQ(MSP_INT_VPE1_TIMER);
} else if (pending & (1 << (MSP_INT_PER - MSP_CIC_INTBASE))) {
msp_per_irq_dispatch();
} else if (pending) {
do_IRQ(ffs(pending) + MSP_CIC_INTBASE - 1);
} else{
spurious_interrupt();
/* Re-enable the CIC cascaded interrupt. */
irq_desc[MSP_INT_CIC].chip->end(MSP_INT_CIC);
}
}
