Eric Lee / smarc-ti-linux-kernel

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Commit b39898cd4077f4b6ec706e717c938751c34e1dc4

Authored by Thomas Gleixner
1 parent 9b66bfb280
Exists in master and in 16 other branches dlt-processor-sdk-linux-03.00.00.04, processor-sdk-linux-01.00.00, processor-sdk-linux-02.00.01, smarc-ti-linux-3.14.y, smarc-ti-linux-3.15.y, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04, ti-linux-3.14.y, ti-linux-3.15.y, ti-lsk-linux-4.1.y

genirq: Prevent spurious detection for unconditionally polled interrupts 

On a 68k platform a couple of interrupts are demultiplexed and
"polled" from a top level interrupt. Unfortunately there is no way to
determine which of the sub interrupts raised the top level interrupt,
so all of the demultiplexed interrupt handlers need to be
invoked. Given a high enough frequency this can trigger the spurious
interrupt detection mechanism, if one of the demultiplex interrupts
returns IRQ_NONE continuously. But this is a false positive as the
polling causes this behaviour and not buggy hardware/software.

Introduce IRQ_POLLED which can be set at interrupt chip setup time via
irq_set_status_flags(). The flag excludes the interrupt from the
spurious detector and from all core polling activities.

Reported-and-tested-by: Michael Schmitz <schmitzmic@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: linux-m68k@vger.kernel.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1311061149250.23353@ionos.tec.linutronix.de

Showing 3 changed files with 22 additions and 4 deletions Side-by-side Diff

... ... @@ -70,6 +70,9 @@
70 70 * IRQ_MOVE_PCNTXT - Interrupt can be migrated from process context
71 71 * IRQ_NESTED_TRHEAD - Interrupt nests into another thread
72 72 * IRQ_PER_CPU_DEVID - Dev_id is a per-cpu variable
  73 + * IRQ_IS_POLLED - Always polled by another interrupt. Exclude
  74 + * it from the spurious interrupt detection
  75 + * mechanism and from core side polling.
73 76 */
74 77 enum {
75 78 IRQ_TYPE_NONE = 0x00000000,
76 79  
... ... @@ -94,12 +97,14 @@
94 97 IRQ_NESTED_THREAD = (1 << 15),
95 98 IRQ_NOTHREAD = (1 << 16),
96 99 IRQ_PER_CPU_DEVID = (1 << 17),
  100 + IRQ_IS_POLLED = (1 << 18),
97 101 };
98 102  
99 103 #define IRQF_MODIFY_MASK \
100 104 (IRQ_TYPE_SENSE_MASK | IRQ_NOPROBE | IRQ_NOREQUEST | \
101 105 IRQ_NOAUTOEN | IRQ_MOVE_PCNTXT | IRQ_LEVEL | IRQ_NO_BALANCING | \
102   - IRQ_PER_CPU | IRQ_NESTED_THREAD | IRQ_NOTHREAD | IRQ_PER_CPU_DEVID)
  106 + IRQ_PER_CPU | IRQ_NESTED_THREAD | IRQ_NOTHREAD | IRQ_PER_CPU_DEVID | \
  107 + IRQ_IS_POLLED)
103 108  
104 109 #define IRQ_NO_BALANCING_MASK (IRQ_PER_CPU | IRQ_NO_BALANCING)
105 110  
kernel/irq/settings.h
Diff comments   View file @ b39898c
... ... @@ -14,6 +14,7 @@
14 14 _IRQ_NO_BALANCING = IRQ_NO_BALANCING,
15 15 _IRQ_NESTED_THREAD = IRQ_NESTED_THREAD,
16 16 _IRQ_PER_CPU_DEVID = IRQ_PER_CPU_DEVID,
  17 + _IRQ_IS_POLLED = IRQ_IS_POLLED,
17 18 _IRQF_MODIFY_MASK = IRQF_MODIFY_MASK,
18 19 };
19 20  
... ... @@ -26,6 +27,7 @@
26 27 #define IRQ_NOAUTOEN GOT_YOU_MORON
27 28 #define IRQ_NESTED_THREAD GOT_YOU_MORON
28 29 #define IRQ_PER_CPU_DEVID GOT_YOU_MORON
  30 +#define IRQ_IS_POLLED GOT_YOU_MORON
29 31 #undef IRQF_MODIFY_MASK
30 32 #define IRQF_MODIFY_MASK GOT_YOU_MORON
31 33  
... ... @@ -146,5 +148,10 @@
146 148 static inline bool irq_settings_is_nested_thread(struct irq_desc *desc)
147 149 {
148 150 return desc->status_use_accessors & _IRQ_NESTED_THREAD;
  151 +}
  152 +
  153 +static inline bool irq_settings_is_polled(struct irq_desc *desc)
  154 +{
  155 + return desc->status_use_accessors & _IRQ_IS_POLLED;
149 156 }
kernel/irq/spurious.c
Diff comments   View file @ b39898c
... ... @@ -67,8 +67,13 @@
67 67  
68 68 raw_spin_lock(&desc->lock);
69 69  
70   - /* PER_CPU and nested thread interrupts are never polled */
71   - if (irq_settings_is_per_cpu(desc) || irq_settings_is_nested_thread(desc))
  70 + /*
  71 + * PER_CPU, nested thread interrupts and interrupts explicitely
  72 + * marked polled are excluded from polling.
  73 + */
  74 + if (irq_settings_is_per_cpu(desc) ||
  75 + irq_settings_is_nested_thread(desc) ||
  76 + irq_settings_is_polled(desc))
72 77 goto out;
73 78  
74 79 /*
... ... @@ -268,7 +273,8 @@
268 273 void note_interrupt(unsigned int irq, struct irq_desc *desc,
269 274 irqreturn_t action_ret)
270 275 {
271   - if (desc->istate & IRQS_POLL_INPROGRESS)
  276 + if (desc->istate & IRQS_POLL_INPROGRESS ||
  277 + irq_settings_is_polled(desc))
272 278 return;
273 279  
274 280 /* we get here again via the threaded handler */