On 08/10/2017 12:10 PM, Alexandru Gagniuc wrote:
> On 08/10/2017 08:07 AM, Alexey Brodkin wrote:
>> ARC cores on reset have all interrupt lines of built-in INTC enabled.
>> Which means once we globally enable interrupts (very early on boot)
>> faulty hardware blocks may trigger an interrupt that Linux kernel
>> cannot handle yet as corresponding handler is not yet installed.
>>
>> In that case system falls in "interrupt storm" and basically never
>> does anything useful except entering and exiting generic IRQ handling
>> code.
>>
>> One real example of that kind of problematic hardware is DW GMAC which
>> also has interrupts enabled on reset and if Ethernet PHY informs GMAC
>> about link state, GMAC immediately reports that upstream to ARC core
>> and here we are.
>>
>> Now with that change we mask all individual IRQ lines making entire
>> system more fool-proof.
FWIW, hsdk doesn't boot to prompt with this patch !
I was queuing up hsdk support and ran into this !
-Vineet
>>
>> Signed-off-by: Alexey Brodkin <abrodkin at synopsys.com>
>> Cc: Eugeniy Paltsev <paltsev at synopsys.com>
>> Cc: Alexandru Gagniuc <alex.g at adaptrum.com>
>
> Tested-by: Alexandru Gagniuc <alex.g at adaptrum.com>
>
>> ---
>> arch/arc/kernel/intc-arcv2.c | 3 +++
>> arch/arc/kernel/intc-compact.c | 14 +++++++++++++-
>> 2 files changed, 16 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arc/kernel/intc-arcv2.c b/arch/arc/kernel/intc-arcv2.c
>> index f928795fd07a..cf90714a676d 100644
>> --- a/arch/arc/kernel/intc-arcv2.c
>> +++ b/arch/arc/kernel/intc-arcv2.c
>> @@ -75,10 +75,13 @@ void arc_init_IRQ(void)
>> * Set a default priority for all available interrupts to prevent
>> * switching of register banks if Fast IRQ and multiple register banks
>> * are supported by CPU.
>> + * Also disable all IRQ lines so faulty external hardware won't
>> + * trigger interrupt that kernel is not ready to handle.
>> */
>> for (i = NR_EXCEPTIONS; i < irq_bcr.irqs + NR_EXCEPTIONS; i++) {
>> write_aux_reg(AUX_IRQ_SELECT, i);
>> write_aux_reg(AUX_IRQ_PRIORITY, ARCV2_IRQ_DEF_PRIO);
>> + write_aux_reg(AUX_IRQ_ENABLE, 0);
>> }
>>
>> /* setup status32, don't enable intr yet as kernel doesn't want */
>> diff --git a/arch/arc/kernel/intc-compact.c b/arch/arc/kernel/intc-compact.c
>> index 7e608c6b0a01..cef388025adf 100644
>> --- a/arch/arc/kernel/intc-compact.c
>> +++ b/arch/arc/kernel/intc-compact.c
>> @@ -27,7 +27,7 @@
>> */
>> void arc_init_IRQ(void)
>> {
>> - int level_mask = 0;
>> + int level_mask = 0, i;
>>
>> /* Is timer high priority Interrupt (Level2 in ARCompact jargon) */
>> level_mask |= IS_ENABLED(CONFIG_ARC_COMPACT_IRQ_LEVELS) << TIMER0_IRQ;
>> @@ -40,6 +40,18 @@ void arc_init_IRQ(void)
>>
>> if (level_mask)
>> pr_info("Level-2 interrupts bitset %x\n", level_mask);
>> +
>> + /*
>> + * Disable all IRQ lines so faulty external hardware won't
>> + * trigger interrupt that kernel is not ready to handle.
>> + */
>> + for (i = TIMER0_IRQ; i < NR_CPU_IRQS; i++) {
>> + unsigned int ienb;
>> +
>> + ienb = read_aux_reg(AUX_IENABLE);
>> + ienb &= ~(1 << i);
>> + write_aux_reg(AUX_IENABLE, ienb);
>> + }
>> }
>>
>> /*
>>
>
